Important news, Glads! Updating your IOS to version 7 would reset your progress in the game. To be able to restore the save file after OS update, please synchronize the game with facebook and/or iCloud before you upgrade your iOS. We are working hard to release an update that would allow you to keep your game's progress and upgrade your iOS safely. We recommend you not to update OS until the release of such update, which is going to be out before the end of September. We sincerely apologize for the inconvenience caused!
More information on I, Gladiator official forum.