If you have not quit the game and triggered Xbox Live syncing, you could try deleting the save in system storage and downloading the online save (not sure if you can do that with the game still running, and there isn't really any way to control or confirm syncing).
Unfortunately, there is no way to get a save off an Xbox to be able to do anything with it...
Maybe try clearing the cache, and see if that makes a difference when you reload the save.
- press and hold the Xbox button on the front of the console for 10 seconds until it shuts down
- unplug the power cable and wait 30 seconds
- pug the console back in and turn it on
- log into the same Xbox Live account you were using, start the game and let it sync, if required