Yes, you should be able to upload new files, and make them available for sale. Here is the process we would suggest:

1. In the Resources tab in the in-browser text editor, one by one, delete an old image and upload a new one, making sure to use the same filename on the new images, as you used on the old image.

2. Generate a preview of the book to see if everything is working properly. This will update all the ebook formats a Leanpub-generated book is available in (i.e. PDF, EPUB, and MOBI).

3. Publish a new version of your book. This will make the newly-generated book available for sale, and this new version will also be what existing readers of your book will get, the next time they click a link to download it.

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