No, going to Hogwarts wasn’t still required.
Attendance at Hogwarts stopped being mandatory after the Dark Lord’s death, since JKR says that though Hermione did, Harry and Ron both never graduated from Hogwarts and instead went straight into working for the Ministry. If they were breaking the rules, presumably they couldn’t be hired by the Ministry, as the Ministry is responsible for enforcing the laws of the British wizarding community.
JKR: Yeah, did they graduate from Hogwarts?
SU: Yes, did they?
JKR: Harry and Ron didn't go back, Hermione did. Did you bet right? You must've, I mean, come on. No one's gonna think Hermione wouldn't go back.
SU: I predicted, yeah.
JKR: Of course she'd go back. She has to get her N.E.W.T.s. Ron was really done with schooling. It would be kind of tempting to go back just to mess around for a year and have a break, but he goes into the Auror department. He's needed. Anyone. Anyone who was in that battle on the right side, Kingsley would want them to help clean up the-- I mean, anyone who's old enough to do it, who's over-age. But Kingsley would've wanted Ron, Neville, Harry and they would've all gone, and they would've all done the job.
- Interview with J.K. Rowling (17 December 2007)
As Harry and Ron both got careers in law enforcement without having graduated, attendance at Hogwarts must have stopped being required by law after the Dark Lord’s death.