It is possible for us to update manually by uploading all of the files that were updated by the steam client.(using ftp or file manager) There is a dedicated server folder in the game directory. We could back up the files by downloading from the server, then we could upload all the files that were updated over-writing the old files. In theory this would work but it would be a fair bit of work and I've not tested to see if it works.
I already checked and the same files that are on the dedicated server exist also in the dedicated server folder of the game client. It is simply a matter of finding the files that were last modified on the date and time that you updated your game client via steam.
Try this at your own risk. As I mentioned it SHOULD work, in theory but I have not tested it.