load winning scene when completed race

I got this script that goes along with a checkpoint script, it has a static variable that counts how many laps the player has completed, what I want to do is load a winning scene or overlay when the player completes 3 laps, I tried using the update function but when the player completes the lap goal the script continues loading the next scene and makes the game unplayable? is there a better function I can use ?

here's the script:

 import UnityEngine.SceneManagement;
 var checkPointArray : Transform[]; //Checkpoint GameObjects stored as an array
 static var currentCheckpoint : int = 0; //Current checkpoint
 static var currentLap : int = 0; //Current lap
 static var startPos : Vector3; //Starting position
 var checkpointText : UI.Text;
 var lapText : UI.Text;
 
 
 function Start () {
     //Set a simple visual aid for the Checkpoints
     for (objAlpha in checkPointArray) {
         objAlpha.GetComponent.<Renderer>().material.color.a = 0.2;
     }
     checkPointArray[0].GetComponent.<Renderer>().material.color.a = 0.8;
     
     //Store the starting position of the player
     startPos = transform.position;
 
 
 
 }
 
 
 function Update(){
  if(checkpointText)checkpointText.text = currentCheckpoint.ToString();
   if(lapText)lapText.text = currentLap.ToString();
 
 }
 
 // load next scene or show game over overlay when the set number of laps is completed