we need to move our current Mobile VPN License Server to a new server. I'm unable to find detailed instructions for doing so. IF we move the licensing to a new server will we have to reconfigure all clients manually?
You'll need to re-license the clients -- because they'll be looking for the old license server. The only way to really avoid that would be to stand up the new license server at the same IP (or change what the DNS hostname points at, if you used a FQDN.)
WatchGuard Customer Support