If she's gotten worse lately, has there been a trigger for it? Apart from what you're doing with her when she's done it, I don't know what else to suggest. One thing I do do with mine is that I tend not to make them apologise in the heat of the moment - I make them go to their room for a little while (usually a few minutes only) and let them think about what they've just done and they are usually a lot more contrite and when they apologise when they come out, they usually mean it then instead of an angry/forced apology, but Im not sure if that would work for her either?