There are several reasons you may want to do a full upgrade on your appliance. This process will upgrade your rescue partition as well as your running partition. During the full upgrade process your current configuration will be removed. You may want to save a copy of it to import or reference later.
Follow these instructions to use use the .nru file to first upgrade your rescue image, and then upgrade the software running on the appliance.
Blue Coat recommends you have a console connection to the appliance. The console connection makes knowing when the .nru install is done easier, and it makes completing the factory reset easier, and most of all, it makes adding the networking information after the fresh install go a little easier.