I have only taught my six year old to narrate, so I don't have experience with an older student, but I wonder if she needs more guidance to help her understand narration. Here are some things I thought about. (Ignore any that you have already tried.)
She is old enough for you to have a discussion about the purpose of narration. When we tell or teach someone else something, we learn it ourselves. Make sure she knows that it is not a test, but is the lesson. Narration is how she will learn the material most effectively. You are not asking for a summary. You are asking her to RETELL the passage, in as much detail as she can remember. This will enable her to internalize it.
Then, maybe give her some very simple examples of what the difference is between what she has been doing and what you are looking for. Start with a story she knows. For example, here is a narration that doesn't give enough details. "Once there was a girl who had to work very hard, then she went to a party and tried on a shoe and then was very happy." Can she recognize the story?
Now try "Once there was a girl who lived with her stepmother and two stepsisters, because her own parents had passed away. The stepmother made her work very hard. The girl wore torn clothes and had so much soot and ashes in her hair that her stepsisters started calling her 'Cinderella'." and so on. Talk about the difference.
Perhaps have your daughter practice narrating simple stories or tales that she already knows, pretending she is telling a younger child (or actually telling a younger child if you have one!) Then work up to new material that she reads and narrates, but make it very easy content. Fairy tales would be great for this. The Blue Fairy Book probably has at least a few that she has never heard. http://www.mainlesson.com/display.php?author=lang&book=blue&story=_contents Ask her to retell the story to make it as interesting as possible for the child (real or imaginary) who is listening. As her skill grows, then go back to narrating her school books. Even if you take a few weeks off of reading the books you would normally assign, just to teach narration, the benefits will be great.
I found when my DD was starting to narrate that it helped if I took a turn narrating, so that she could hear plenty of examples of what I expected. Once you move back to narrating her school books at her level, you could do a chapter every so often. It would help her understand, and might also help you discover any challenges in the process that you can help her work through. Narration isn't easy! It really makes you think.
Anyway, as I said, my DD is young so I'm not an expert, but maybe that will get you thinking about some ideas that will help.