try this..
In your child window write one javascript function for close..
function close()
{
window.opener.location.href = 'http://parentPage.aspx?fromChild=1';
self.close();
}
call this function on close..
ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "onAddNew", "close()", false);
In your parent page PageLoad check the query string..
if(Request.QueryString["fromChild"]=="1")
{
BindGridView();
}
hope this helps..
Vote it if solved your problem