Have you tried the old butter on the paws thing?
We did it with our cat when we moved house. If you can find your cat and take it to your new house, keep it indoors for a day or so (yeah, i know, easier said than done) then you take the cat outside into the back garden and rub it's paws with butter (front and back paws). your cat will sit there licking its paws clean for ages. The theory is that as the cat sits licking, it surveys its new surroundings and associates them with you (its best source of food), and decides to hang around your new gaff rather than buggering off.
Might be an old wives tale but it seemed to work for our mangy moggy
