Ok this trick only works if you don't have any prompts on the dashboard page. They can live on other pages if you want to keep them.
Add a text element to your dashboard
<META HTTP-EQUIV = "REFRESH" CONTENT = "900">
where 900 is the refresh time in seconds. Don't forget to check the Contains HTML Markup box.
Till Next Time.
Edit: Stijn pointed me to adding:
<META HTTP-EQUIV="CACHE-CONTROL" CONTENT="NO-CACHE" >
To avoid caching of the browser.