So you probably know the neighborhood there really well. Can you ask your current employers if there is a neighborhood listserv and if they would be willing to put a message up saying that their terrific nanny will be leaving them when school starts in case anyone is looking, etc...
That's how we found our nanny and it was fabulous for everyone. She still sees her old family, knows half our neighbors well, knows the neighborhood and playgrounds, etc... and we felt so comfortable knowing how strong the referral was.
Good luck!