How to make a Java script restart?

You can use invoke repeating to repeat a function. Example:

 var projectile : Rigidbody;
 
 InvokeRepeating("LaunchProjectile", 6, 6);
 
 function LaunchProjectile () {
    
     var instance : Rigidbody = Instantiate(projectile);
     instance.velocity = Random.insideUnitSphere * 5;
 
 }

This will wait 6 seconds (as soon as the play button is pressed) and then activate 'LaunchProjectile' function, it'll repeat the same function every 6 seconds too.