http://411mania.com/movies/ben-affleck-only-contracted-for-justice-league/
As of this time, Ben Affleck is only contractually set to reprise his role as Batman in the two Justice League films. Affleck’s agent Patrick Whitesell told THR that Affleck’s contract with Warner Bros. has him tied down through Justice League: Part One and Justice League: Part Two, but confirmed that Affleck has in fact written a Batman script that could conceivably move forward.
“He’s contracted to do at least Justice League One and Two, so at least three times wearing the cape…there’s a script that he’s written that is a really cool [Batman] idea, so that’s out there as an option.”
It’s worth noting that Affleck is also set to appear in Suicide Squad, so that cameo apparantly isn’t a part of his core contract. Justice League: Part One begins shooting next month and will open on November 10th, 2017.