You should check local ordinances before considering releasing them. Some states and localities have laws against relocating wildlife to prevent habitat disruption and prevent pest species from spreading.

If you’re steadfast in refusing to kill them, your best bet is to try to prevent them from entering as best you can. Caulk over any gaps in walls/floorboard and around and pipes or vents, no matter how small a hole seems you should cover it because they can squeeze through extremely small spaces. For larger holes you can fill them with steel wool to prevent them from coming in. It might be a bit of an up front investment but it’ll likely be cheaper over all than caring for them every year.