How To Re-Download an App From The App Store
If you accidentally remove an app you purchased on your iPhone (of iPad or iPod touch) before syncing it to iTunes, or if you remove an app from iTunes on your Mac, you can re-download the app without paying for it again.
The App Store keeps track of all the apps you've downloaded - paid for or free - whether you downloaded them directly to your iPhone (or iPad or iPod touch) or into iTunes.
In iTunes, to download an app again, find it in the App Store and click the Buy App button. A dialog window like the one below will open. Click OK and the app will begin to download.
You can re-download an app from your iPhone, too. Launch the App Store and find the app. Tap the price, then tap BUY NOW. A message will pop-up, similar to the one displayed by iTunes. Tap OK to start the download.
Note: Make sure you are signed in with the same account you used to purchase the app originally.
Another important note: If the application is no longer available on the App Store, you will not be able to re-download it.
App Store, iPhone, iPhone App, iTunes, re-download app in How-Tos, iPad, iPhone, iPhone Apps, iTunes 
Reader Comments (3)
I found this verry helpful,
so i would just like to says thanks :-)
OMFG thx1!!!!!!!!!!!
Well, I did as was instructed and guess what!.....I got charged $9.++ something for the app. Too bad I didn't know this ahead of time.