Maybe send an email to Support@teamlava.com and ask them. Or maybe TL can post instructions on this thread since it might be a popular question.
You might still be able to use the Storm8 method to transfer your games to your iPad mini. And then since Restaurant Story is logged onto your original account, you should still be able to play them from either device since it doesn't care which device the games are originally on. Then you can start a new game on the old iPad. Using Restaurant Story on either device, you can log into and out of either set of games. But I'm not sure.