I've cheered for one/two/three years already so that means I'm on varsity next year?
That is false. Teams are not chosen based on years of experience. It is possible to be a 2nd or 3rd year JV cheerleader.
Note: Seniors are not allowed to be on a JV team; HOWEVER, that does NOT mean they automatically make varsity. It IS possible to be cut from the cheer team entirely if you do not possess the necessary skills to move up to varsity your senior year.