Eep - you're not gonna like this answer. It's a waiting game. Gems and passes will be refilled after a period of time passes - about twenty minutes. And you will, unfortunately, max out on both, so you can't just leave the game for a few days and return. The only other way it, well, paying real money for currency. Go ahead if you think it's worth it, but the more patient among you will be able to play the game without paying.