increase 1 just one time

i have this script and its increasing ones like crazy. the problem is simple when points go up to 10 add 1 to level (just one time)

 static var level:float = 0;

function Update () { if(Player.points==10){ level +=1; } }

Update runs once every frame, so don't use it. Just add one to level whenever the points go up, not every frame.