Due to security restrictions certain browsers will not allow you to refresh a page from an external site that is framed in your site. To get around this, load a local page into the frame. Use the Javascript onload event to redirect the page to the external site.
This page illustrates the code - view the source: Frameset refresh example.
There is a major problem with this - the frame will reset when the browser is refreshed and hence you'll loose your place in the framed website.