I really like this #lavenderlives argument from the hp wiki talk page for Lavender Brown:
Having Hermione save Lavender, and showing it to us in such a dramatic fashion (she “shrieked” NO! before blasting Greyback), Rowling is showing us that Hermione, whatever she may have felt about Lavender, didn’t allow any lingering resentment to stop her for a second from doing what was right. It’s also a kind of feminist statement that, even though girls might be rivals in love, they have to stick together when it’s a war. This was clear as a bell to me when I read it.
Why else would Rowling show Hermione fighting for Lavender Brown specifically, other than to demonstrate yet another of Hermione’s strengths? Hermione might have even hated Lavender, or at least we wouldn’t have blamed her — a teenager in love — for doing so, but she rose above those feelings and showed her true colors there, showed her unwavering goodness. Rowling would not have placed all the emotional weight on Hermione of having to save Lavender just to have her die later of her wounds, a death unmentioned no less.
Rowling is far too good a writer for that kind of carelessness, especially given the comments in the archive-cited NBC interview on not killing characters lightly. This was a serious test for Hermione, and, as always, she shone brilliantly.
I believe the significance of the action for Hermione’s character, combined with the fact that the last mention of Lavender was of her still “feebly stirring” (thus alive), makes clear that JKR meant for Lavender to live and should encourage you to consider revising your stand that the clarity of the film death overrides the lack of clarity in the book. To me, the evidence I’ve presented here suggests strongly that she did in fact survive in the book.
It might seem too literary-analysis for an encyclopedic website, but I like the point it’s making, and overall i think it’s good evidence supporting Lavender’s survival.