You don't need to repot Utricularia. They have no roots but stolons (thin, whitish growth shoots that grow through the substrate). Once it fills the pot simply divide it in e.g. 4 parts and soon you'll have 4 pots full of thriving Utricularia.
After some time a lot of moss and algae may start to grow on top. Often it is possible to simply cover the whole pot with some fresh substrate or sand and the buried Utric will very soon resurface with new vigour. But it is always a good idea to have a backup in case it does not work out as intended.
It is also possible to make leaf cuttings if you have problems with unwanted species like U.subulata or U.bisquamata: Pick a few leaves of the right species, put them in water in a well lit position and wait until new stolons, traps and leaves sprout from them. Then pot them up. Utricularia grow fast (and exponentially). so they will fill a pot even from a small piece.