I solved this by putting the following script on the parent page.
<Script type="text/javascript">
var win;
function OpenPopup(id, mode) {
if(mode === '1')
win = window.open("/Jobs/Extras/ProjectExtra.aspx?id=" + id, "List", "left=300, top=150,scrollbars=no,resizable=yes,width=860,height=680");
else
win = window.open("/Jobs/Extras/ProjectExtraInvoice.aspx?id=" + id, "List", "left=300, top=150,scrollbars=no,resizable=yes,width=860,height=680");
return false;
}
var timer = setInterval(function () {
if (win.closed) {
clearInterval(timer);
window.location.reload();
}
}, 1000);
</Script>