Loss of highlights in certain chapters of a ebook

Hej, 

For some reason, the highlights are missing and have been lost in certain chapters. As, I see it in my library, it shows that I read the book one month ago, because of which my highlights are missing in the new chapters I read. Do you have any idea how I can retrieve the highlights back (or the previous read version of the book), because I have been reading the book continuously?

What steps should I take in the future, so that this issue doesn't happen again (So basically how do I make sure my highlights are saved all the time when i mark them)?