We did a second year with our last AP. Pros - not having to train someone new, kids already comfortable with AP and the agency charges slightly less (maybe 1k less?) the second year.
Cons - our AP slacked in her second year. She also seemed to expect more from us in terms of gifts and general generosity. By the end, no matter what we did for her, it never seemed enough. I also think when they’ve been in the US two years, and with a single family for those two years, it’s harder for them to leave. Maybe they have a serious boyfriend or they start to think that you’re their family, so there’s a lot of big emotions when their contract finishes.
I wish I would have done 1.5 years!