As Moooots suggested, you can save a copy of your save to external media. If you have a flash drive or an external hard drive with enough room to hold your save file, just copy it over (you'll do this under the settings menu, specifically under storage, just look for your Minecraft files and copy them).
I did this constantly on my first world, for the same reason, and never had a bit of trouble when it came to reverting to a backup when I goofed up my world badly enough.
Edit: I should mention when I say "Settings Menu" I'm talking about on the Xbox Dashboard, and NOT inside Minecraft. I don't know if you can do it from inside the game.
http://www.youtube.com/user/PSUTerra