Hotspot: handle known clients

Hello
My hotspot is configured with mac-cookie for 30 days.
So if a known/registered user comes back within 30 days, he is automatically logged in by RouterOS and surfs transparently, he does not even see the portal page.
I would like to add a page like “Welcome back! your time left is blah blah blah” for such users, is there a way to force known clients to be redirected somehow when they are back?