ActionScript 3.0 :: Delete Line Shape If Button Is Pressed Again?

I have a line that is being drawn following a route when a play button is pushed. At the end of the movieclip the whole route is shown with the beginning and end. How do I clear that line if the user hits play again? Right now it connects the beginning and ending points and creates another line on top of the old one.

Actionscript Code:

var shape : Shape = new Shape();shape.graphics.lineStyle( 4, 0x9C1E26);shape.graphics.moveTo( arrow.x, arrow.y );addChild( shape );addEventListener( Event.ENTER_FRAME, loop );function loop( event : Event ) : void{    shape.graphics.lineTo( arrow.x, arrow.y );}