[SOLVE] Target lock missile script - how to make it keep searching for new target

So I got this script from this forum, thanks to DexRobinson (he made it).

So I'm using his script, and it works perfectly. The problem is that once the target of the missiles are gone, they will just travel forever. I want them to keep searching for a new target... I instantiate 5 missiles at once.

 using UnityEngine;
 using System.Collections;
 
 public class Missle : MonoBehaviour {
 
         public string searchTag;
         private GameObject closetMissle;
         private Transform target;
            public GameObject missileExpObject;
     
         void Start()
         {
             closetMissle = FindClosestEnemy();
            
             if(closetMissle)
                 target = closetMissle.transform;
         }   
        
         void Update()
         {   
             transform.LookAt(target);
             transform.Translate(Vector3.forward * 5.0f * Time.deltaTime);
         }
        
         GameObject FindClosestEnemy()
         {
             GameObject[] gos;
             gos = GameObject.FindGameObjectsWithTag(searchTag);
            
             GameObject closest = null;
             float distance = Mathf.Infinity;
            
             Vector3 position = transform.position;
            
             foreach(GameObject go in gos)
             {
                 Vector3 diff = go.transform.position - position;
                 float curDistance = diff.sqrMagnitude;
                
                 if(curDistance < distance)
                 {
                     closest = go;
                     distance = curDistance;
                 }
             }
            
             return closest;
         }
     void OnTriggerStay(Collider otherObject)
     {
     if(otherObject.tag == "Enemy") //&& playerEntered)
             {
             
             var expPrefab = Instantiate(missileExpObject, this.transform.position, Quaternion.identity);    
             Destroy (this.gameObject);
             Destroy(otherObject.gameObject);
             Player.Score +=100;
             print ("explode enemy");
             }
     }
        
     }