Titanium Backup - You can use free version found on Market to backup & restore. No need to buy the premium version.
-You need to first ROOT ur tablet to make use of this app !
You need to see this video first to see how to do a backup & restore and also to know difference between Free & Pro version.
Now basically just by watching the video above, you will understand the use of this application; but the above video doesn't explain how to restore when you've flashed a new firmware (fresh install) and have a clean slate with no apps except for already included-in-ROM system apps.
From the video, u will learn that you have to run "Batch"; then choose one of the choices to backup.
I choose "Backup all user apps + data". This option doesn't back up system apps & data; which is not needed as you're doing a fresh firmware install; therefore old settings may cause problems etc.; so better to avoid that.
Once you backup; it creates a new folder with all apps & data in your Tablet's root directory. Now what we need to do is to find that folder and then to transfer it & keep it safe in our PC.
To do that; connect ur tablet to the PC. Once u do it; notice there's a notification in lower right corner of screen which shows 2 options - USB debugging & USB Storage. Choose "USB storage" ; follow the steps & choose "USB storage ON".
Then a new window will pop up on ur PC which will show u all internal folders on ur tablet. Find the folder named "Titanium Backup" and copy & paste it somewhere in ur PC.
Now, we have our apps & their data safe in our computer. And we're ready to install new firmware without any worries.
Once you've installed new firmware & have access to market; install Titanium Backup again from Market. Then connect ur tablet to PC & switch on "USB Storage ON". Then copy Titanium Backup folder which u had saved in ur PC & paste it in Tablet's directory of folders from where u had copied it previously.
Now disconnect USB & open Titanium Backup; choose "Batch"; then choose "Backup all user apps + data". Then it should automatically detect the folder. If it doesn't, then go back to options; choose "Settings"; choose "Backup Folder" and navigate to "Titanium Backup" folder. Then go back to Batch & choose "Backup all user apps & data" and u're done.
All ur apps are back & u don't need to find them all again or to buy them again.