Updating cover in 'other books by author'

So, over the past years, I’ve paid an artist to redo most of my book covers because the originals, from when I was a younger author, aren’t the greatest. I’m currently preparing for the re-release of the last book that needed a better cover. Most places, I can update it easily enough (inside ebooks in the ‘other books by author section,’ etc.

However, I only now realized that the old cover is also on the back of one of my paperbacks (another ‘more by author’ section). I’m still in touch with the artist and could probably pay them to swap out the thumbnail cover. But is this worth it or should I just leave a published paperback cover alone? Especially when I don’t sell many to start with?