how to play audio when a level is complete

I want to do it like this. I have a script called levelCounter. There are 5 levels in my game. I just want that if my character returns to my main scene and finishes a level… the music in the main scene changes.
I have a code like this on my music objec where the music is attached:

var audio1 : AudioClip;

var audio2 : AudioClip;

function Update()

{ if(levelCounter.level1==false){

audio.clip = audio1;

audio.Play();

}

if(levelCounter.level1==true){

audio.clip = audio2;

audio.Play();

}

}

You could do something like this:

void OnLevelWasLoaded(int level)
{
    if (level == 2)
    {
        levelCounter.level1 = true;
    }
}

Or just increase the levelCounter when you go to a new level in your game with Application.LoadLevel …