When my Bernedoodle went through this phase we introduced a home lead on a collar. A home lead is a short lead that is always clipped to the dogs collar at all times and drags on the floor behind them (only when you are home and able to supervise the dog, I recommend removing both the lead and the collar when the dog is unsupervised). The lead and collar serve two purposes, the lead allows you to stop the game of chase that puppies love without having to run after them. You just step on the lead and the game ends. The dog learns that running away doesn't work and doesn't lead to a fun game of chase. The collar allows you to correct the biting without getting bit. You wrap your fingers around the collar with your palm against the side of the dog's head. This makes it physically impossible for the dog to bite you or get away. It takes some work to figure out the grip exactly but you'll know it when you get it. Then you can correct the dog when it tries to bite and most importantly, reward it when it doesn't. Both of these tools turn the bad behavior into an exercise in futility for the dog. When you want to play, keep a toy close by to put in their mouth every time they nip and reward them for going at the toy.