Go into your App Store app. At the bottom go to updates & at the top there should be a purchased tab that goes across the top of the screen. Click on it & it should show all the apps you have downloaded in the past. At some point you will have to sign in with your Apple ID if you hadn't already. Go down the list & click the ones you want to re-download. It's time consuming & a pain. You will also have to reorganize your folders.