That might be too big of an app to download over the air-especially if using data plan.
Have you tried to update by connecting to iTunes?
You could also try this:
Go to Settings - General - Date & Time, and turn off "Set Automatically", then change the date to, maybe, one year ahead. Then try to download the app again. (Turn on "Set Automatically" again afterwards.)
There's also the possibility to go to the App Store - Featured, scroll down to your Apple ID, tap it, sign out, then sign in again with your existing Apple ID.