You have to use Javascript for that.
eg:
<script language="JavaScript">
function clearText() {
document.FORMNAME.TEXTBOXNAME1.value="";
document.FORMNAME.TEXTBOXNAME2.value="";
document.FORMNAME.submit();
//etc
}
and on the submit button:
<input type="button" value="Submit" onClick="javascript:clearText()">
</script>
WARNING: DONT USE THIS SCRIPT AS-IS BECAUSE WHEN SUBMITTED NONE OF THE VARIABLES GET PASSED. JUS LOOK AT THE CODE AND CHANGE IT ACCORDING TO YOUR USE. ONCE AGAIN, THE SCRIPT AS GIVEN ABOVE WONT WORK.