After uploading, you can always update your book (including the files, metadata, and the prices) and save the changes. There is no need to withdraw the book or upload an 'updated' version.
You can't make any changes right after sending your book to stores when it is shown as Under review.
During this time, your book is under a manual and automatic review by our staff: we are checking for direct store links and publicly available content, among other issues. We are also checking if the book is already available in stores where you are trying to send it to. Processing should not take longer than a few working days.
Once your book has passed processing, it will be sent to stores and shown as Processed. Your book will be reassigned to you, and you’ll be able to edit it again.
Just click the "View and edit" button to edit the book, then press "Edit" again to unlock your book page. You'll be able to change anything (price, title, description, etc.), or even upload an updated version of your book. (To upload a new file, simply drag & drop it in the file field.) You can always download your already uploaded files with the little download arrow in the top right corner.
You can change everything without withdrawing the book, even upload a new file. (If you are running into errors, please check this article.) Your changes will be sent to stores once you press "Update" and take place within a few hours or days.