You could set the maximum time in the deck options: e.g. set it to 1 month, and all cards will have that as the next interval if you answer them right. After you work through the cards, you can increase this maximum. There's a chance, however, that after all this time you'll have many of cards reset back to beginning.

Or, you can fire up the desktop card browser and reschedule all the cards in those decks—choose "return to the learning queue" so they pop up like new, or set some interval like, again, a month. Then you can do a “custom study” to work through the cards right away. (I haven't tried this method, though, so not sure it will work.)