Rookie Scribe
I would venture to guess that if she were open enough to let you know that she feels your sex life is becoming boring, then she would also be open enough to have a frank discussion of how you'd go about improving it. So, I definitely agree with those who noted that you should talk about it. In one aspect, you are lucky that she has come out and said something, so many won't. Now, it's up to you to work with her and try different avenues.