How to change bitmap without adding another child to the stage

I know exactly what this function is doing, however I don't know how to change it so that the 3 symbols only ever add once and only the bitmaps change. Thank you for your help! It's probably something simple, but I can't seem to figure it out, I am an intermediate as3 programmer but still have some holes in my knowledge.

var randCount:int = 3
        function loadImage():void
        {
            for(var i:int = 0; i<randCount; i++)
            {
                var imgLoader:Loader = new Loader();
                var imgRequest:URLRequest = new URLRequest();
                imgRequest.url = "../img/planet" + int(2*Math.random()) +".png";
                trace(imgRequest.url);
                imgLoader.load(imgRequest);
                imgLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, onLoadedImg);
            }
        }

        function onLoadedImg(e:Event):void
        {
            e.currentTarget.removeEventListener(Event.COMPLETE, onLoadedImg);
            var bmp:Bitmap = e.currentTarget.content;
            bmp.x = 600;
            bmp.y = Math.random() * 520;
            bmp.width = 80;
            bmp.height = 80;
            addChild(bmp);

        }
button.addEventListener(MouseEvent.CLICK, changeBitmap);
        function changeBitmap(event:MouseEvent):void {
            loadImage();
        }