Reading levels are a guide to help you and the school have an idea where your child is at but it is not a rigid 'this is what your child has to read' so I second/third/fourth that let her read the book, mark in her reading log how she found it, then have her read another book of her own choosing.
They is to read, to practice, to keep doing it. And not just harder books, different books - long books with chapters, short stories, factual books, atlas, poems, plays, comics. It is about having fun.
And children have steep learning curves. DD has just been put up 2 levels at school after an accurate enough assessment at school, possibly not quite right but it did not matter. Over summer DD has gone on leaps and bounds on her own with no school books and has jumped enormously with her comprehension. The books she has now are still too easy, so we practice saying the characters' lines with different tones, talking about the story, what is going on, what is her favourite bit, character and why. And then we read our books from home. And she LOVES magazines now moshi monsters.