Date countdown reset

Question

I've been using the below code for a countdown timer that ends on 5th April 2012. However when the countdown reaches this date I'll like it to automatically start counting down to 5th April 2013. Currently it goes into minus numbers. Thanks in advance for any help.
this.onEnterFrame = function() {
    var today:Date = new Date();
    var currentYear = today.getFullYear();
    var currentTime = today.getTime();
    var targetDate:Date = new Date(currentYear,3,5);
    var targetTime = targetDate.getTime();
    var timeLeft = targetTime - currentTime;
    var sec = Math.floor(timeLeft/1000);
    var min = Math.floor(sec/60);
    var hrs = Math.floor(min/60);
    var days = Math.floor(hrs/24);
    sec = String(sec % 60);
    if (sec.length < 2) {
    sec = "0" + sec;
    min = String(min % 60);
    if (min.length < 2) {
    min = "0" + min;
    hrs = String(hrs % 24);
    if (hrs.length < 2) {
    hrs = "0" + hrs;
    days = String(days);
    var counter:String = days + "  " + hrs + "  " + min + "  " + sec;
    time_txt.text = counter;

Answer 1

currentYear wasn't defined in my last message.  this is a more efficient countdown timer that doesn't require repeated creation of new dates:
var today:Date = new Date();
var currentYear = today.getFullYear();
var currentTime = today.getTime();
var targetDate:Date = new Date(currentYear, 3, 5);
var targetTime = targetDate.getTime();
var startTime:Number = getTimer();
this.onEnterFrame = function() {
    timeLeft = targetTime-currentTime-getTimer()+startTime;
    if (timeLeft<0) {
        targetDate = new Date(currentYear+1, 3, 5);
        targetTime = targetDate.getTime();
        timeLeft = targetTime-currentTime;
        startTime = getTimer();
    timeLeft/=1000;
    var days:Number = Math.floor(timeLeft/(60*60*24));
    var hrs:Number = Math.floor((timeLeft-days*24*60*60)/(60*60));
    var min:Number = Math.floor((timeLeft-days*60*60*24-hrs*60*60)/60);
    var sec = Math.floor(timeLeft-days*60*60*24-hrs*60*60-min*60);
    time_txt.text = formatF(days)+"  "+formatF(hrs)+"  "+formatF(min)+"  "+formatF(sec);
function formatF(n:Number):String {
    var s:String = n.toString();
    while (s.length<2) {
        s = "0"+s;
    return s;