Jeremy,
In order to upgrade SDC, you have to download the latest SDC Server installer, and run it on the system that is running the SDC server, the installer will ask you to upgrade your current server, just follow the installer flow and at the end you will have the latest SDC server. If you want to run the upgrade in an unattended mode, you can use the same configuration file you use to run the original install.
For more information about install process please go to:
http://www.genuitec.com/sdc/docs/sdc_installation.html
Best Regards
Ignacio
SDC Support