ActionScript 3 :: How To Redraw Shape Using Only Code

My question is: how do I redraw a shape using only code? Short comment on the task itself. I've an eventListener, which grabs clicks on stage and stage resizes. Both execute the same function - redrawEvents(evt:Event). The stage contains a number of blocks, which represent certain events. On each redraw these blocks are repositioned, and also lines (which represent connections between events) are drawn.

Any way to reposition all the blocks, but I got stuck on redrawing lines. I'm using a single shape to hold all the lines, because lines, unlike blocks, are not interactive. Since the whole point of the application is creating sets of interconnected events, I have to modify this shape every time a new block is created, which also calls redraw function. Here's the code I use to modify the shape

stage.addEventListener(MouseEvent.CLICK,redrawEvents);
function redrawEvents (evt:Event) {
var lines:Shape = new Shape();
lines.graphics.lineStyle(2, 0xFFFFFF, .75);
lines.graphics.clear();
for (var k:int = 0; k < connections.length; k++){
lines.graphics.moveTo(eventList[connections[k][0]].x + 50, eventList[connections[k][0]].y + 50);
lines.graphics.lineTo(eventList[connections[k][1]].x + 50, eventList[connections[k][1]].y + 50);
} addChild(lines); }

However, whenever the shape is modified, it still leaves the 'older versions' of itself on screen, and i don't want that. I tried to create and delete instances, various type conversions.