There isn't just one AP Economics exam - there's macro and micro.
There's this class which covers the material for AP Macroeconomics: http://economicsforhomeschoolers.blogspot.co.uk/
I've heard good things about the PA Homeschoolers AP class but unless your DD is interested in economics, I see no need to spend so much time on it. Her time may be better spent covering the personal finance course and maybe AP World History if you were looking for an AP class.
You don't need to get an AP class syllabus approved unless you want to put "AP _____" on her transcript instead of "______ with AP exam" and her score next to it.
It sounds like your daughter's going to have a fun few years but it may mean a little extra stress for you. ^_^