Don't think there's really any precedent for us to compare it to, but considering avatar is the 3d movie i'm sure there's going to be demand for it, and I doubt there's too many people, specially if the audience is mostly made up of big fans and newcomers, who after seeing avatar in 3d wont want to watch the sequel.
The probably shouldn't do a month long re-release with a massive marketing campaign, but having it run for 2 weeks with an avatar 2 trailer attached should do more good than bad