Hello!
Steps to update the game server:
1. Ensure you've made a backup of the "Data" folder inside the game server installation.
2. Download the new version of the server and overwrite your current installation with it (you can find the actual download link on this page http://wiki.atomictorch.com/CryoFall/Server/Setup section "Installation").
3. Place ServerIcon.png file in "Data" folder if you want to have a custom icon instead of default one (should be 64 KB max size).
4. Start as usual.
Your "Data" contains the server settings file and world savegame so you will not lose anything.
BTW, now it's possible to adjust the server rates! Just edit the "ServerRates.config" file in "Data" folder!
Regards!