Add to the same mind map after each session. I would consider a link for characters, have the character details radiating off that, Plot have plot details radiating off that, theme, setting etc all on one mind map so that you can add to it after each activation session and see it all come together. How you actually do your mind map is ultimately up to you. Certainly create one mind map and clean it up by making a new one when you're done activating the book.
Alex
