Your Book Creator projects are stored in a location based on what version of operating software you are using.
Locate the folder called A&I Book Creator Projects and back it up to an external folder.
Macintosh HD/Library Application/
Macintosh HD/Users/Your Login Name
Next copy your folder that contains your images. If you images are scattered all over your computer now is a good time to consolidate and copy them to one folder. Name it something useful like My Book Images.