May be the next-next expansion will contain updated cards, who knows, I hope it will be less cost-contained, I really think you deserve the success your game is having.
The problem is usually when you go outside standard deck sizes. Then the cost usually increases a lot. As the same principle as of that books only can have pages as a multiples of 16 (and therefore many books has a few empty pages in the back), card piles can only be done in certain sizes. They can be smaller, but you have to pay for the whole size anyway. (if next limit was 72, those three cards would add cost as the whole difference between a 54 deck and a 72 deck). That costs adds to the game price, so you as a designer and a publisher have to consider if it's worth it.