Using Business Intelligence Dashboard Designer : Using Content Linking to Create Interactive Dashboards : Setting the Refresh Interval
  

Setting the Refresh Interval

The content in your dashboard may need to be refreshed periodically if users are examining real-time data. You can set refresh intervals for individual panels on your dashboard or for the entire dashboard.
To set the refresh interval for individual panels in the dashboard, click the edit button and the select the panel that contains the content you want refreshed within the Objects panel. Under Refresh Interval (sec) enter the interval time in seconds and click Apply.
If you want the entire dashboard to refresh, click the Prompts tab in the dashboard and set your refresh interval.