Hi ,
check this once it can do what you want
<script language ="javascript" >
var tmp;
function f1() {
tmp = setTimeout("callitrept()", 2000);
}
function callitrept() {
document.getElementById("Button1").click();
}
</script>
</head>
<body onload="f1()">
In the above code Button1 is id of button which you want to perform click operation
All the Best