I already know, that if you put 8.1 preview on your system, your recovery partition is also updated. There's a whole thread on getting 8.0 back on (make sure you make a recovery USB before).
Here is a nice video guide. It's for the Pro, but I have successfully used it on my Surface RT twice.A nice, helpful person on XDA Developers posted the USB recovery image in this thread:
USB Recovery EN-US RT 8.0 - xda-developers