Countdown timer that triggers random movie clip load

1

I need help. I have this code here to count down every 10 seconds and load an external random movie clip. It works once, but I would like to have it start the timer again–can anyone help me to achieve this?

code:

displayTime = 5;
function countDown() {
displayTime–;
if (displayTime == 0) {
clearInterval(timer);
trace(“Times Up”);
container1_mc.loadMovie(“ball”+(Math.floor(Math.random()*3)+1)+".swf", “_root.movieclip”);

}

};
timer = setInterval(countDown, 1000);