[tor-relays] How to restore fingerprint on updated RPI3

I've run a relay for over a year and recently updated from an RPI2 to a RPI3. I've copied the torrc file and the node has the same IP Address and ports. What additional files need to be copied to get the fingerprint (et al) to match the original relay. The updated RPI3 shows up as a new relay and I would like to have it take over the old fingerprint.

Any suggestions or procedures? Thanks in advance!