Just for a test, try moving the bedroom RPi much closer to the living room if possible.
Strictly speaking, you need to try shortening the distances to the router, since the communication between the devices will always have the router in the middle (unless you set up an ad-hoc network without a router). Moving the Pi in the bedroom won't help if the router is also in the bedroom, for example. Shortening the distances, check for possible interference from other routers (neighbours' networks), rebooting the router, etc. can all help. Many routers have quite poor software which can degrade the router performance over time, and a reboot can help in such cases. If you have an Android device, there are WiFi analyzer apps available to help find less congested spaces in teh WiFi spectrum.