Is a lot of the issue that she doesn't adjust her vocabulary and syntax to suit the occasion? My DS-now-8 had on a couple of school reports things like "At times, it can sound as though [DS] is reciting a passage from a textbook". He would get carried away and not notice when people weren't interested (though if they were interested and joined in, I think he was always just as happy to listen as talk). That was a problem that we and school worked on.
However, I think part of it was just a consequence of advanced language skills. If your language is age-typical, it doesn't often matter if you don't learn to adjust your language to the occasion, because your natural speech mode is what your peers expect. If your language is advanced for your age, it does often matter, because you have to learn to speak in a way that will be understood by your age peers. We talked about it, but I felt this was an instance of his being asked to learn a skill that most children his age don't have, not an instance of his lacking age-typical skills.
In both aspects he's a lot better now. He will still talk about Minecraft to me even though I have zero interest, sometimes to the point that I impose "no more Minecraft talk today". I completely agree that it's appropriate for you and other people to place limits.
