Great title for a sequel... wait for it... wait for it...
"28 Years Later". It could take place 28 years after the 1st film. You could see how some things have changed and also what kinds of things would not have changed. It would be like a progression, you see. Then the movie could be about how events unfold 28 years after the events of the first film.
-- Sent from my 13 year old P.O.S. Desktop®