Why didnt the Cullens come back in New Moon when Bella was almost killed by Laurant?

well, i guess since edward told alice not to keep tabs on bella and since the wolves were pretty close, so i guess she couldnt see it

Jacob says in one of the books that they made sure that the vampire (laurent) was going to kill bella before they attacked him SO IM GUESSING that they were already close to Bella to be watching therefore Alice couldnt see Bella because the wolves were already close to her :]
Thats just my guess though :P

i dont really know

yea i felt this part was wierd too.. why could Alice see her jump off a cliff but not when Laurent was going to kill her? i was sure Alice would've seen that and that was when they were going to return to save her and keep her safe..

Edward did tell Alice not to keep and eye on her so she wouldnt have seen it that way.

Remember that Alice cant see the wolves and when Bella was with Laurent the wolves were ACTUALLY ON THEIR WAY so her fate was mixed with theirs and Alice wouldn't have been able to see her being attacked at all.