I don’t know the deck, of which you speak, but can you not add Reverse cards to it?
If you cannot, it might be easier if you were to migrate the cards to a Reverse Note Type, such as the “Basic (Optional reversed card)” Note Type. See here for some instructions.
You could export your deck to CSV, add the “y” in the Add Reverse column for all cards, or only those, for which you want the reverse option and then reimport the CSV. In this way you are only updating your cards and not losing your statistics. NB Back up your deck before you start, in case you make an error.
See here for steps to follow.