I agree with the Chinese School route, but recommend Powerspeak if you're going to use an online program. I've used both Powerspeak and Rosetta Stone and prefer Powerspeak because it offers game-based learning and (according to my language teachers) teaches better grammar/real-world language. There's a company called Toniks, which offers online language tutoring, but I haven't used their program.

Daa'iyah Na'im
Director/Head of School
The AGVI Academy for Gifted Youth
http://AGVIgifted.org