Emma, I went through a phase of Alex having a party at bedtime. But honestly, try to keep the bedtime as early as possible, offer her a book or something that she can do quietly telling her that if she wants to stay awake that's fine, as long as she doesn't come out of her room. If she is happy leave her. I remember when Alex was around Abbi's age there was a huge thread on the go about children of the same age all having parties at bedtime, it lasted about 2 months and then she settled again.
Hope the same thing happens for you too, but I would try to do as little as possible to avoid AP at this stage.