Как переделать таймер что бы он обнулялся каждые 3 дня?

Question

[mrzgt]

function get_timer() {
			var timeend= new Date();
			timeend = new Date(<?php echo $date_out; ?>);
			var day = new Date();
			day.setMonth(day.getMonth() + 1);
			day = Math.floor((timeend-day)/1000);
			var sec=day%60; day=Math.floor(day/60);
			var min=day%60; day=Math.floor(day/60);
			var hour=day%24; day=Math.floor(day/24);
			if(day<10)day='0'+day;
			if(hour<10)hour='0'+hour;
			if(min<10)min='0'+min;
			if(sec<10)sec='0'+sec;
			var timestr =  "<span class='special-timer-info'>" +day+  "<span class='special-timer-text'><?php echo $day; ?></span></span><span class='special-timer-line'>&ndash;</span><span class='special-timer-info'>"  +hour+    "<span class='special-timer-text'><?php echo $hour; ?></span></span><span class='special-timer-line'>&ndash;</span><span class='special-timer-info'>"  +min+   "<span class='special-timer-text'><?php echo $minute; ?></span></span><span class='special-timer-line'>&ndash;</span><span class='special-timer-info'>"   +sec+   "<span class='special-timer-text'><?php echo $second; ?></span></span>";
			document.getElementById('time_out').innerHTML=timestr;
			setTimeout(get_timer,1000);
		}
		get_timer()