They don't mind having some room at their roots. Re-pot him, no problem...in a pot one or two sizes bigger than what he's in. They like a nice loose soil...I use store bought potting mix with extra perlite added.
They can be dry to the touch before watering again...I use the first knuckle rule...if the soil is dry up to the first knuckle on the finger I stick into the soil I give it a drink.