Simple Tween Question

Hi all, I am using a simple tween, which basically tells my movie clip to remember it’s original _y position and then from there move back -200, this works really smoothly. Once it plays it goes to a stop. The issue is after the stop I again tell the movie clip to move back -200, but it still uses the original _y position… Anyone know hoe to make it use the _y position the first animation ends on?

onClipEvent (load) {
	this.originalY = this._y; //stores original position
	this.tween("_y", this.originalY - 200, 1.5, "easeOutBack", 2);
}