We asked her about those Buffy remake plans and she seems as perturbed by the whole thing as the show’s fans. When we asked her what she thought of Buffy without Joss she said, "Yeah, and that's a very big mistake in my opinion.” Whedon wrote both the 90s movie and ran the subsequent spin-off television show she was a part of. So it makes sense that Hannigan says, “I mean if Joss isn't involved, it's only the title."
And without Joss, there’s no way they’ll get her involved in it. Not even for a cameo. She says, "Not without Joss. Joss is the only reason that we would go back. I mean, it's just ridiculous to think of that TV show without Joss. That's just silly to me… And all the fans know that, too, so I don't know what they're thinking."
Hannigan’s reaction to remake echos that of former Giles Anthony Stewart Head, who, rather gleefully trashed the notion a few weeks ago here. Look it's no mystery why they’re doing this. Vampires are hot and let’s face it, Twilight is basically just a watered down Buffy ripoff so why not bring back the real deal and get rich.
source