I wrote a memoir about my childhood based on what I remember and what I was told. I didn't know anything much about my past, how to write a book, or research that goes with it. I was adopted. So, without the research I just rushed through with writing and self publishing the book. Since then I've located my biological parents and did research. I have all the research documents and people to back me up. How can I used what I have to rewrite my memoir? How so I explain the rewrite? Can I use a different title for my book?
You can do anything you want since this is your book, and your story. "Revised editions" or second editions of books are much more common with textbooks than memoir, but there are lots of people who write more than one memoir of their life. The late great Leonard Nimoy is a case in point. I AM NOT SPOCK was published in 1975. I AM SPOCK was published in 1995.
You might think about writing a completely different book rather than revising. That will solve the biggest problem you face which is reader confusion.
You don't want readers to think they've already read the book if you want them to buy the revised and expanded version. Also, you don't want people to think it's a different book and be angry cause they'd read
the first version.
You can use a different title, but that makes it a new book.
You can call it an updated, revised, expanded version and use the same title but you MUST put "parts of this book originally appeared in an edition published in X" OR "this edition is a revised, expanded version of TITLE published in X"
Nothing gets a reader annoyed like thinking they've been hoodwinked by old books being sold as new.
And you might address the issue of the revision/expansion/update by writing a preface to this new book, saying what you said here: you've got more info and more story.
The rule here is to be transparant with your readers and buyers.