Hrm, I don't know if a legacy cannon could do it, but there are some extremely large (but extremely rare) hyperspace systems out there. Hoshi no Iori, for example, has a hyperspace system, and it's the size of a small solar system -- it's never been tested, though (but it should work, hopefully, if the dice roll lucky). Yamatai's Empress Palace also has a fold drive large enough to (again, theoretically, and with a good die roll) move the planet. Systems this big are generally not safe for anything but one-time emergency use, but since that's what you need, I'd say it's possible to try.
Of course the best thing for the planet is to avoid such emergencies in the first place. If the Lorath do (and it'd take a long time) build a massive fold system, I'll be assigning it a percentage chart for success, failure, and critical failure (very bad) based on construction quality (read: how well roleplayed its construction is).