I was just thinking about this! I'm taking a quickie course on Mandarin (I speak Canto) and the program Rosetta Stone was mentioned. I hear it really does work and I know many schools use the program as a reinforcer. Unfortunately, it *is* pricy, but you should still check it out:

http://www.rosettastone.com/en/

You can also approach your instructor and ask for one-on-one training to improve your proficiency. Adult schools sometimes offer more advanced classes, too. I know a local adult school that offers conversational Japanese while the local community college only offers an introduction to Japanese.