Just leave them in the airing cupboard for a few days and they'll shrink back down again
The idea is you soak and expand them to semi fill them with water which then evaporates during play to cool you down, and not help with bounces or anything like that. Once it's dry just spread the crystals out across the band and then soak or wet it until it's a bit inflated but not blown up completely, then enjoy the moist Planet coolness.