Settings > iTunes & App Store > Automatic Downloads > Music/Apps
How To > http://support.apple.com/kb/ht4539
Troubleshoot > http://support.apple.com/kb/ts3688
Download Past Purchases
- Sign in with the Apple ID that you used for the original purchase. See which Apple ID you used to download an item.
2) See if the content is available for redownload. Previously purchased items might not be available if they're no longer on the iTunes Store.