你可以这样:

    window.onload=function(){
        var send=document.getElementById('send'),
            times=60,
            timer=null;
        send.onclick=function(){
          // 计时开始
          
         timer = setInterval(function(){
             send.value = times + "秒后重试";
             send.disabled = "disabled";
             times--;
             if(times == 0){
                 send.value = "发送验证码";
                 send.disabled = "";
                 clearInterval(timer);
                 times = 60;
            }
         },1000);
        }
    }

if(times<0){
   clearInterval(timer); 
   send.setAttribute("value","重新发送验证码");
   send.removeAttribute('disabled');
这里加  //  times=60;  // 第二次无效是因为times已经是-1了。直接成立if条件停止了。要重置times为60.
 }else