Sure.
Maybe I'll start with the last suggestion. The simple remedy of banning somebody from seeking office again strikes me as being problematic from the point of view of the charter. Frankly, it also instinctually offends my democratic sensibility. It occurs to me that candidates' primary focus is on getting themselves elected, not on managing their books. One can imagine situations pretty easily in which it's really the official agent's fault, but the candidate gets banned from running. Perhaps we should ban the person from becoming an official agent if they can't handle it. That would actually be less legally problematic. I'm not sure it would actually resolve the problem.
What does strike me as resolving the problem to some degree is to just ban loans. Wouldn't that solve the problem of unpaid loans into the future? Everything else I think of has to be draconian. You have to find some way of punishing people so severely that they won't want to do this in the future. It strikes me that you either download the problem onto somebody else.... Candidate X runs for office and overspends the limit—I know I'm shifting from loans here to people overspending their limit—so we now impose a burden on the campaign, which then gets transferred to the riding association or the party. Meanwhile, candidate X has wandered off. They were really in it for one shot, and their only concern was whether or not they got elected. They really don't care about the institution and essentially don't care whether their failure involves additional costs being imposed on somebody else.
We could change it to make it a personal liability, but that would be something that millionaires could laugh off but that would be a brutal imposition on those who are less well off.
Everything you do tends to come back to the same kind of problem, so why not move to the most obvious one and say that you have to raise the money, that you can't borrow money?