The Skyview will retain the active flight plan across the power cycle. If you load a flight plan, go flying, then land and shut down, that flight plan will still show in Skyview when you power up. No part of the route will now be active. If this was at your destination, just select "Reverse Route" for the Skyview to flip the plan. Put the cursor on the the first point you wish to fly to and either select "Direct" or "Activate Leg" as you wish. You do not have to have the USB in for any of this to happen.
I like to save lots of routes. Because they are text files, a small USB stick will hold an almost unlimited number of them. I keep a very small USB in the port for this purpose. This stick can also store a screen shot or save a backup of your configuration etc so it is convenient to keep one in there. After any route is loaded (anytime from then on including after powering up the Skyview again) you can simply choose "Export Flight Plan" and it will be saved to the USB. It will be named using your origin and destination and look like "KATL to KTPA.GPX" At home you can remove the USB with the exported plans, put that into your computer and rename the file to something you more easily recognize. Just leave the .GPX on the end of the file name. When the USB is back in the Skyview you can choose to import the flight plan and you will see it with the name you gave it.