Lets say I have a game. In this game you pick well berries then you go in a portal to the town and sell your berries. I'm not sure how to get it to update to universes. I do know how to make it save and load the berries just not through universes.
Well to start with, you'd have to use the Data Store, not Data Persistence. So with Data Stores you'll probably want to designate a Store for each player (via Player.UserId works best I believe), and in that store you should have a value for the number of berries picked and number of anything else that can be picked.
I haven't had a whole lot of experience yet with Data Stores, so I can't be much more specific, but that concept should be what you need.