If they do reuse the old stuff, 'recanonize' as you are calling it, that would be a bad idea. Namely because of all the confusion it will cause. "This Jaina is not the same Jaina as the one in the books. Yes, she is Han and Leia Solo's daughter. No, she doesn't have any brothers. Yes, I know that in the books she does. No, this is not the boo-. Yes, her name is Jaina. But she doesn't have any... Why are you walking away?"
If they're going to put all the previous non-Movie stuff as non-canon, better let it rest on it's own, and not bring back some of the more popular elements, cuz you'll just muddy the pot then.
I think you're seriously overcomplicating the issue. I don't see how it would be confusing to anyone. The entire Star Wars fan base who actually care about Jaina already know about this. The people who don't won't even know there WAS a Jaina before these films. And if any new fans look into this, they'll see the nice big "THIS DIDN'T HAPPEN; LEGENDS" sticker on any of her old stories. Perhaps they could slap a new sticker like "TOTALLY DISNEY CANON APPROVED" on new stories that ARE canon.
As consortium said, if this was that bad of an issue, it would already have been an issue effecting the prequel trilogy. Sure, they kind of sucked, but it had nothing to do with confusion about what's canon; it had to do with Episode 1 being 'god awful', Episode 2 being 'meh', and Episode 3 being 'kind of alright'. No one, to my knowledge, had any trouble following the new prequel trilogy, or any of the EU that span of of it because "This totally contradicts the accounts of the Clone Wars we were given in the Thrawn Trilogy or in Marvel Comics' Star Wars 68: The Search Begins! I don't know what's canon anymore!"
And to be clear; the contradictions in those, especially Star Wars 68, are a doozy. I mean, according to Star Wars 68, the Mandalorian Protectors fought for the Empire (They didn't), alongside Storm Troopers (They didn't), under the command of Boba Fett (Nope.), and that during this time Fenn Shysa became familiar with Princess Leia (Hadn't been born yet.)
Or the confusing claim that the early batches of clones that the fleet went up against during the clone wars were crazypants and dangerous. Ya know. Even though one would assume the fleet in question, being an Imperial Fleet, had fought for the Republic, and thus would have been fighting ALONGSIDE the not-all-that-crazy Clone Army. The entire character of Joruus C'Boath is a confusing head-scratcher that had be given all sorts of retcons to make sense.
Yet the prequel movies failed to tank because of this. No one was baffled by why the new movies contradicted their established EU.
I may favor the old EU to their new canon, at least for the foreseeable future, but I hardly think continuity confusion will be a major issue they'd face simply be rebooting characters' stories.
Comics have been brought up and frankly that's an excellent place to draw another example from too. DC has, off the top of my head, rebooted their continuity no less than 2-3 times. Yet people still seem to manage to enjoy the new comics as they come out. (Sort of. I personally hate the New 52, but that has nothing to do with being confused as to what's canon. It's because the New 52 has largely been written by idiots. And any of the writers who AREN'T idiots, have had their work made more stupid via executive meddling.)
I fully understand that just because the character of Batman is still called Batman, it doesn't mean that his pre-52 adventures are still canon. Some might be, if they choose to reference them, but I don't ever get confused by why a New 52 Batman comic is contradicting an old Batman comic. I understand, this is a new continuity.
Star Wars fans, I dare say, are at least as smart, on average, as your average DC comic fan. I think we can give them the benefit of the doubt and assume they're capable of wrapping their head around the concept of 'a continuity reboot'.
tl;dr, I think you're seeing a problem that simply isn't there. People are smart enough, on average, to understand that a continuity reboot means that new material over-writes the old material. No one asked why the Dark Knight Batman didn't know the Joker, even though he'd fought him in a previous movie.