Chris Perez doesn't have an upcoming book release that I'm aware of, and honestly, I think his publishing days are likely over. His writing was so tied to documenting his life with Selena, and after 'To Selena, With Love,' there wasn't much of a public push for a follow-up. He seems focused on his family and music career now.
I'd love to be wrong, though. If he ever did decide to write again, maybe something reflecting on his life since then or his perspective on fatherhood could be interesting. But checking his socials and the usual publisher catalogs, there's just no buzz. For now, his legacy is firmly and beautifully that one book.