Getting the right people into the lawmaking body, who will make the change.

I'm assuming the hypothetical weird situation where public advocacy outside the lawmaking process is illegal, but the lawmakers in the lawmaking process can discuss and repeal that law. This isn't implausible in democracy, as it is common in democracies that lawmakers have immunity from prosecution based on objectionable speech in a parliament.

Or illegally via advocating (just because an action is illegal, it does not mean it can't happen) or motivating the lawmakers in various ways, eventually a revolution (which still can be democratic in a sense).

If lawmakers can't repeal that kind of law legally, the system is not a sovereign democracy, but, at best, restricted/controlled democracy, by someone else than demos, who is maintaining that superlaw.