Question about co-author royalties

Hi, I'm a psychologist and a new self-published co-author with a specific question.  I co-authored a book with a patient about her amazing recovery from mental illness (now sustained for several years).  We spent equal time writing, but she's done the vast majority of the promotion work in the year and a half since publication.  We originally agreed we’d promote together and she'd get 70% of the royalties because it's primarily her story.  Now she may take over all the promotion work from this point forward and it's very possible that her current efforts could lead to hugely increased sales.  My question is should we change the royalty percentages and, if so, what should they be?