Re-run authentication flow without logging out

Currently I have a custom login flow. Users log in with the username/password form, then they select a group from a dropdown. The selected group is added to the token.

Now if a user wants to select a different group he has to log out and re-authenticate.
Is there a way to re-run then auth flow without logging out? Then the user/pass form is skipped and the user can select a new group.