Reloading current page after a user subscribes

We've got some pages that have a mix of unprotected "preview" content, a subscription form (visible only to non-subscribers), and protected "premium" content. I can use shortcodes to control what a person sees when they go to the page. But when somebody signs up, I want to reload the same page so that they can now see the premium content. How to do this?

Thanks,

jon