Step 1 - Reset your current iPad to factory settings, wiping out all information on you iPad.

Step 2 - Sell your current iPad

Step 3 - Delete your current device from iTunes. I have never done this for only one device, I usually just delete them all and then reauthorize the ones I keep.

Step 4 - Sync your new device with iTunes. You can sync all of the apps your purchased without needing to buy any of them a second time.

Step 5 - Enjoy!