What should I do if I want to redesign the cover of the original book and raise the price? Do I need to reapply for the application number?

If a book has been published, we must start with the quality if we want to raise the price. First of all, the cover should be attractive. If there are no characters on the original cover, you can ask the hand-drawn artist to draw the story characters and insert a few more figure paintings on the inside page. Actually, it's the quality of the paper. You can change the paperback into the hardcover. Of course, whether you reprint or redesign the cover for publication, you need to reapply for the application number, and the book number is a bit expensive, so please carefully consider whether this book is worth it and whether there are other factors such as market.