I commented and suggested using a meta refresh to reset countdown timer automatically. When countdown timer time ended then meta refresh reshes the whole page and countdown timer starts from the 30 seconds. This process will continue again and again and never stop. It's a method to reset countdown clock timer using Meta refresh and also you can set any value using PHP programming.
<!DOCTYPE html><html><head><title> Refresh countdown timer automatically</title></head><body><?php $phpvar="30"; ?> <script>function countDown(secs,elem) {var element = document.getElementById(elem);element.innerHTML = "Timer: "+secs+" seconds";if(secs < 1) {clearTimeout(timer);element.innerHTML += '<meta http-equiv="refresh" content="0; url= ">';}secs--;var timer = setTimeout('countDown('+secs+',"'+elem+'")',1000);}</script><div id="status"style="font-size:30px;"></div><script> countDown(<?php echo $phpvar; ?>,"status");</script></body></html>
<!DOCTYPE html>
<html>
<head>
<title> Refresh countdown timer automatically</title>
</head>
<body>
<?php
$phpvar="30";
?>
<script>
function countDown(secs,elem) {
var element = document.getElementById(elem);
element.innerHTML = "Timer: "+secs+" seconds";
if(secs < 1) {
clearTimeout(timer);
element.innerHTML += '<meta http-equiv="refresh" content="0; url= ">';
}
secs--;
var timer = setTimeout('countDown('+secs+',"'+elem+'")',1000);
</script>
<div id="status"style="font-size:30px;"></div>
<script> countDown(<?php echo $phpvar; ?>,"status");</script>
</body>
</html>
