how do i...?

on page 55 of Already Ready by Katie Wood Ray & Matt Glover they write about Regan who is lead into writing a story about her dramatic play experience of going on a picnic. how do I create play experiences we can later write about? currently we are "playing" the same thing over and over again (and I don't really want us to write about the kids acting out bribing the cops). do i just need to wait for a natural opportunity and be ready to jump on it the next day, or do i prompt their play to reflect a more natural story?