1) You can add following tag in head of aspx page where (content="5") 5 is second of the interval for refreshing the page.
<meta http-equiv="refresh" content="5">
so in your case (2*3600) makes 2 hours refresh.
2) If you are adding download link dynamically so on each refresh toggle by viewstate variable and do remove/add of the hyperlink(<a> </a>) part so downloads gets restricted/allowed.