[Action Script] Changing "y" value of yoyo tween May,2012

I have buttons set on yoyo like so:

var myTween1 = new Tween(upClose.buttonOne, "y", Regular.easeInOut, 100, 115, 1.3, true);
myTween1.addEventListener(TweenEvent.MOTION_FINISH , onFinish1);
function onFinish1(e:TweenEvent):void{
myTween1.yoyo();
}

At some point, I have to change the y values of this yoyo tween.
I tried mytween1.stop(); and then write another function with different y values but it just stops the previous tween and doesn't create a new one.
I know there must be a way to simply change the y values in the existing function...Or do I have to kill the first one first and if so, how?
HELP
Thanks.
Changing "y" value of yoyo tween

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