enemy targeting player in different scene

Hi.How do i make enemy from another scene to target the player when he goes on other scene ? (The enemies on level 2 Will target the player when the player Will be on level 2 )... I tried this but I've got a null reference exception

 var Distance;
 var Target : GameObject;
 var lookAtDistance = 25.0;
 var chaseRange = 15.0;
 var attackRange = 1.5;
 var moveSpeed = 5.0;
 var Damping = 6.0;
 var attackRepeatTime = 1;
 
 var TheDammage = 40;
 
 private var attackTime : float;
 
 var controller : CharacterController;
 var gravity : float = 20.0;
 private var MoveDirection : Vector3 = Vector3.zero;
 
 function Start ()
 {
     attackTime = Time.time;
     target = GameObject.Find("Health");
 }
 
 function Update ()
 {
     Distance = Vector3.Distance(Target.position, transform.position);
     
     if (Distance < lookAtDistance)
     {
         lookAt();
     }
     
     if (Distance > lookAtDistance)
     {
         GetComponent.<Renderer>().material.color = Color.green;
     }
     
     if (Distance < attackRange)
     {
         attack();
     }
     else if (Distance < chaseRange)
     {
         chase ();
     }
 }
 
 function lookAt ()
 {
     GetComponent.<Renderer>().material.color = Color.yellow;
     var rotation = Quaternion.LookRotation(Target.position - transform.position);
     transform.rotation = Quaternion.Slerp(transform.rotation, rotation, Time.deltaTime * Damping);
 }
 
 function chase ()
 {
     GetComponent.<Animation>().Play("run");
     GetComponent.<Animation>()["run"].speed = 1;
     GetComponent.<Renderer>().material.color = Color.red;
     
     moveDirection = transform.forward;
     moveDirection *= moveSpeed;
     
     moveDirection.y -= gravity * Time.deltaTime;
     controller.Move(moveDirection * Time.deltaTime);
 }
 
 function attack ()
 {
     if (Time.time > attackTime)
     {
         GetComponent.<Animation>().Play("attack");
         GetComponent.<Animation>()["attack"].speed = 1; 
         
         Target.SendMessage("ApplyDammage", TheDammage);
     //    Debug.Log("The Enemy Has Attacked");
         attackTime = Time.time + attackRepeatTime;
     }
 }
 
 function ApplyDammage ()
 {
     chaseRange += 30;
     moveSpeed += 2;
     lookAtDistance += 40;
 }

Can someone help me please Thank you !