My understanding is that a normal backup in iTunes of your iPad will save all game progress. So, all you have to do, before doing the jail break, is (1) connect your iPad to iTunes and select "Transfer Purchases." This will ensure all data on your iPad is transferred to iTunes. Then, (2) select "Back Up" in iTunes.
After iTunes finishes the back up, you should be good to go. If you need to restore the backup, then that information should be there.
I am willing to be corrected on this, but I've not noticed that I've lost any information when I had to "restore from backup." It was all there. The key is that you must not get any errors in creating the backup...
Hope this helps and reassures.
Marilyn