Updating a variable from one script from another or alternative ideas for a solution

I am new to unity and I am hoping to get some feedback on a design issue I've encountered. As I have looked on here the more I believe that my current implementation is flawed and open to alternative views! Thanks in advance.

I am working on a multiplayer game which players are supposed to collect items from a level, the thing is I would like for the items they collect to respawn after some time.

Currently if the player collides with an object the player script despawns the item and I would need to communicate to the item script that there is one less active item.

Player Script

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.Networking;
 using UnityEngine.UI;
 
 public class Controller_Player : NetworkBehaviour {
 
     // Threshold is used to determine the distance a player falls before respawning
     public float threshold;
 
     // Assigned an empty game opject for spawn point to be assigned
     public Transform playerSpawnPoint = null;
 
     public float powerTimer;
 
     public float speed;
     public float speedMod = 1.0f;
     public float jumpHeight = 100.0f;
     private bool onGround = false;
 
     // Physics component
     public Rigidbody rigidbody_ref;
 
     ScoreScript score;
 
     Camera cam;
     public float distance = 5.0f;
 
     //public Controller_PowerUps pUp = GetComponent<Controller_PowerUps>();
 
    // public override void OnSta()
     //{
         //score = GetComponent<ScoreScript>();
       //  score = GameObject.Find("RoundManager").GetComponent<ScoreScript>();
     //}
 
     public override void OnStartLocalPlayer()
     {
         rigidbody_ref = GetComponent<Rigidbody> ();
         
         score = GameObject.FindGameObjectWithTag("ScoreManager").GetComponent<ScoreScript>();
         //Sets camera target when player is spawned on network
         Camera.main.GetComponent<ThirdPersonCamera>().lookAt = transform;
         cam = GameObject.Find ("Player Camera").GetComponent<Camera>();
 
         powerTimer = Time.time + 10;
         
         //GameObject powerUps = Game
     }
 
     void Start()
     {
 
     }
 
     //Update: Called before a frame is rendered. 
     void Update()
     {
         if (!isLocalPlayer)
             return;
 
         if (Input.GetKeyDown("space") && onGround == true)
         {
             jump ();
         }
 
         // Checks if time for PowerUp has expired
         PowerUpTimer ();
     }
 
     //FixedUpdate: Before any physics is applied
     void FixedUpdate()
     {
         if (!isLocalPlayer)
             return;
 
     // Used to spawn player when falling off the map
         if (transform.position.y < threshold) {
             transform.position = playerSpawnPoint.position;
             rigidbody_ref.velocity = new Vector3(0, 0, 0);
 
             // Also, decrease points of fallen player
             score.SubPoints(1);
             score.SetCountText();
         }
     // Code for player movement
         float moveHorizontal = Input.GetAxis ("Horizontal");
         float moveVertical = Input.GetAxis ("Vertical");
 
         //Ribidbody: class, .AddForce to move RB
         Vector3 movement = new Vector3 (moveHorizontal, 0.0f, moveVertical);
 
         Vector3 actMovement = cam.transform.TransformDirection (movement);
 
         rigidbody_ref.AddForce (actMovement * (speed * speedMod));
 
     }
         
     void OnTriggerEnter( Collider other)
     {
         // Calculates points from ScoreScript
         if (other.gameObject.CompareTag("PickUp"))
         {
             NetworkServer.Destroy(other.gameObject);
 
             score.AddPoints(1);
             score.SetCountText();
         }
 
         if (other.gameObject.CompareTag ("PowerUp")) 
         {
             NetworkServer.Destroy (other.gameObject);
 
             // Cause player to glow, indicates Player has PowerUp
 
             // Check to see which PowerUp was picked up
             //if (other.name == "SpeedUp")
             speedMod = 4;
         }
     }
 
     // OnCollisionStay: Called once per frame for every collider/rigidbody
     //                     that is touching rigidbody/collider
     void OnCollisionStay ()
     {
         onGround = true;
     }
 
     //Calculates force to apply for collision
     void OnCollisionEnter(Collision col)
     {
 
         if (col.gameObject.CompareTag("Player"))
         {
             Rigidbody otherRigidbody = col.collider.GetComponent<Rigidbody>();
             Vector3 test = GetComponent<Rigidbody>().velocity;
 
 
             otherRigidbody.AddRelativeForce(test);
             test = Vector3.Reflect(test, Vector3.right);
         }
 
     }
 
     void jump()
     {
         Vector3 jump = new Vector3 (0.0f, jumpHeight, 0.0f);
         rigidbody_ref.AddForce (jump);
 
         onGround = false;
     }
 
     void PowerUpTimer()
     {
         //Update time
         float timeLeft = powerTimer - Time.time;
 
         //Time expired; reset values
         if (timeLeft < 0) 
         {
             timeLeft = 0.0f;
             speedMod = 1;
         }
 
     }
 }

and item script

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.Networking;
 
 public class Controller_PowerUps : NetworkBehaviour {
 
     public GameObject powerUpPrefab;
     public int numberOfPowerUps;
     private int PowerUpCount;
     public float spawnWait;
 
     float nextSpawn;
 
     public Transform[] spawner;
 
     Vector3 spawnPosition;
 
     // Use this for initialization
     public override void OnStartServer()
     {
         if (!isServer)
             return;
 
         nextSpawn = Time.time + spawnWait;
 
         for (int i = 0; i < numberOfPowerUps; i++)
         {
             Spawn();
             PowerUpCount++;
         }
     }
 
     // Update is called once per frame
     void Update () {
 
         if (nextSpawn <= Time.time && PowerUpCount < numberOfPowerUps)
         {
             Spawn();
             PowerUpCount++;
             nextSpawn = Time.time + spawnWait;
         }
     }
 
     void Spawn()
     {
         spawnPosition = spawner [PowerUpCount].transform.position;
 
         GameObject pickUp = (GameObject)Instantiate(powerUpPrefab, spawnPosition, new Quaternion(0, 0, 0, 0));
         NetworkServer.Spawn(pickUp);
     }
 }