Buy some liquid fertilizer and see what happens. Another suggestion is to try and give it more light or something.
These plants NEED fertilizer without question.

This may sound incredible.....but trust me, it worked for me!
I add ice cubes to the water dish of my Lucky Bamboo, a "trick" I learned from the Chinese lady who lives nearby. If you are using tap water, let it stand for 24 hours to dissipate the chlorine, before pouring into the ice cube tray.

Little need for any kind of fertilizer....it can actually harm the Lucky Bamboo, unless used in GREAT moderation.

I've no idea why the ice works, but my bamboo went from nearly dormant to thriving in just a few days. Another great "Secret of the Orient"?