That’s a little under 31,000 lines. 
If it was me, and it was, going from 3.105 to 3.201 I would reset to factory defaults and reconfigure. If I recall correctly, OpenWRT advises that going from the 18 to the 19 chain but I would do that even if they don’t.
I didn’t have much in my old setup to document/remember/redo: my wifi settings, my openvpn configs, my wireguard configs, nano, adblock and sqm. Took about 10 minutes.