We’re not out of Preview just yet. It’s not strictly defined but the main two things that are keeping us in preview is that the CA app is still a separate app, and Monzo-to-Monzo payments aren’t built in yet.
When you can open your Monzo app on prepaid, upgrade to a current account, get sent a current account card, and then activate it, which will triggering a migration of your prepaid transaction history into the new infrastructure, that’s for the most part when we’d consider it to no longer be a Preview.
To address the original post - we do plan on keeping top-ups in the full current account app for ease of use 