i'm not sure there is a way you could refresh your site.
I think the best way to do this is to create a rule which indicates that the user logged in is a demo user, and in that case you should only allow them to view the pages but not be able to insert or edit.
This could be done using Security Assist because it gives you the ability to set rules based on the user logged in. And then you can use that rule to allow certain functionality.