Deleting the app is severe overkill in most instances. Simply go to your iPad Settings and scroll down to JeppFD-Pro on the left column. Now scroll down on the right side until you see "Reset User Settings" and "Deactivate". Try the "Reset User Settings" option first by turning the switch to green. Now leave Settings and launch JeppFD-Pro and wait for a window asking if you want to reset. Acknowledge and your app is reset back to when it was new. You will lose saved routes but the app should work fine now.
For those that do delete the app, a good wifi internet connection should download all the enroute, terminal charts and manuals in well under 10 minutes. I've performed this update on many iPads. Anything longer is due to a slow connection. With that being said the "Pilot" and "AXS" network at the AOC is a slow network. I've seen up to 35 min. to download everything on that network.