Speaking from my own experience, I would like to advise you to use lacquer thinners to wipe the wallet down (make sure to wipe thoroughly). Bear in mind that this process might have some of the dye of your leather. Then, in order to give the leather it's original finish, re-dye the leather with the original dye that was used on it.
P.S you might want to give your leather some NFO, this will bring your leather additional roundness and fullness.