If you decide you want to make the limit explicit, I still think that the limit should be the same for the upped card. It still has function when played that way.
Also I think the limits need to come up, because what's important is my hand count after the card is played.
If you wanted, you could also make the limit lower, so that the card will only help if you're playing your card and not if you're just sitting there. That would change the dynamic of the card though, so that part is up to you.