Judging by the first X-Men: Apocalypse trailer, the only thing blue about Mystique is her blue-and-yellow X-Men uniform (Am I the only one still having trouble with the concept of Mystique as a member of the X-Men?). However, Jennifer Lawrence recently confirmed that she does get into the traditional blue-skin makeup for a few scenes. "I am blue in it, a little bit. I put my foot down as much as I could. [But] they were very, very nice to me."
Lawrence has made it no secret that she's not a fan of the tedious process that's necessary to craft the blue-skin of Mystique's natural appearance. In the four years since X-Men: First Class, Lawrence's meteoric rise to stardom has also given her the ability to "put her foot down" and tell producer's to limit how much screen-time she has in the blue make-up.
Surely, Lawrence is probably contractually obligated for a certain amount of screen-time in blue-skin but with Lawrence's X-Men contract up after Apocalypse, the producer's are likely trying to appease her requests so that she's more likely to sign up for more films.