One thing that helps with social interaction in Fate is to reverse things. Roll, then act out the result. Because when you start out and try something and eh, the other guy rolled higher, you've kind of set yourself up in a weird way. If you know you win or lose this roll, you have an easier time going for what is said and how it might be said.
It also gives you the option to say "Come on, you succeeded with 3 shifts, gimme a little more here". You can push that onto the dice, making it less personal. It's not you who wants her to come up with something clever, it's the dice, damnit!
In the meantime, you could have the other players chime in. If you go the "dice first" option, the dice demand something big, be it fail or success. You're all in that together now, so you can try to solve it together. You can do the same for "I shoot it" descriptions to come up with something more interesting, so she doesn't feel singled out.
It could also be that she might not have a good grasp on the world, which makes it hard for her to click with the game like that. It's a weird thing for me, I can come up with quite decent dialog in English, I believe, but when I play DFRPG in German, I'm having a hard time, because 95% of my DFing is done in English. I literally don't know what to say. So maybe if she can listen to the audiobooks, get her a bit into the feel of the world, that might help.
It might also be that she doesn't know all that much about the world, so she's unsure of what she can and can't say. This is also a problem I've had quite recently, when my gaming group was so exited to play their childhood system with this epic storyline with tons of important NPCs and all that. Only I've never played that a day in my life. Never read anything on it, I was barely aware it existed. As such, I was completely lost for a long time and still am, so when it comes to dialog, my side of the conversation is rather dull and muted as well. I simply don't know what to say. I don't even know the lingo.
First and foremost, I would be honest. It seems that it's your problem first and foremost and not hers. She might not even be aware that there IS a problem, right? Maybe talk to her in private and tell her that you noticed this and that it feels like she's not getting a connection to the game and ask her what you could do to help. It's probably easier than accusing her of doing something badly. Which, after all, isn't what you are trying to do in the first place. Maybe you can workshop something, if she's up for it. Go over scenes you played and come up with something a bit more fuego for the dialog. Maybe come up with catchphrases for her character, that she can use to spice things up.