Maybe I'm misunderstanding, but can't you just go into iTunes and sync your apps (after you've applied a check to the checkbox for the deleted app in the list of all the apps you've ever purchased.)
Or is the problem that you bought the app on your iPad and never backed it up on iTunes? If you had backed it up on iTunes, it should still be on your iTunes account. On my iTunes apps list, I still have plenty of apps that I've deleted from various Apple devices.