PDF file used to print book, conversion was a disaster, what can be done?

We have a PDF of a book that we published.

Using the conversion process butchered the file, as I see is expected by the help forums here. What other way can I take all these files and make them into an ebook more easily?

Can I convert it or export the individual pages somehow to make them more easily converted into a PDF?

Each page is laid out like a school workbook. With an introduction, objectives, and spaces to answer the questions. Ideally we just want every page to be laid out exactly as they are in the PDF, just in a file to be read by a tablet.

Any help is greatly appreciated!