Is there a way to reset the leaderboard for custom rooms?

Unfortunately the only way to reset the leaderboard is to file a support ticket. You can indicate specific users to reset if need be or whole entire stats. Use https://recroom.happyfox.com/new to file a ticket for leaderboard resets.

With a bit of planning, you can implement version numbers into your leaderboard stats such that you always know which players have stats that are utilizing outdated circuitry. Either allocate one of the stats or use integer packing to encode the version number into a multipurpose stat. Then, once your testing is done, you can increment the version number and your circuit will migrate everyone with an outdated version number.