My read on Caesar is that he's the kind of person that would absolutely never commit suicide directly, because it would be too undignified, but might expose himself to danger with the hope of dying gloriously as he did.
Napoleon was deliberately modeling his life after Caesar and seemed to have made multiple attempts at letting himself be killed, using similar logic. He was just too damn "unlucky" to ever take a fatal shot.
It's safe to assume Caesar would've gone on his expeditions if he hadn't been assassinated. But it seems very plausible he hoped something like the Ides of March would take place.
That, to my mind, is the best explanation for why he exposed himself to such obvious danger.
It makes a lot more sense than the idea that he became lazy, stupid, arrogant, or incompetent about his own personal security. Something he had previously been incredibly meticulous about. Of course it's true that we'll never know for certain.