To download the latest version, simply visit the general App Store and search "bigoven."
Download the first result that appears, titled "BigOven 350,000+ Recipes and Grocery List."
Once you've downloaded the latest version of the app, you can remove the old one by holding down on the previously existing BigOven app icon and tapping the "X" icon that appears.
That's it! Now you're all set to start using the new and improved iPad app. Simply tap the remaining BigOven icon on your home screen, log into your BigOven account, and all of your recipes will automatically sync.