Thank you Lei. I am just learning it as i am new to Tableau Community.
An option would be to use subscriptions.
If after the extract has been refreshed, a subscription is run against the view, it will refresh the underlying data (ie not use the cached query)
This means that the next time someone opens the dashboard they will get the latest data
You could also use the tabcmd get command to do the same thing, and schedule using Windows Task Scheduler
Hope this helps