if it's in an ornimental pot you might try planting it in the ground as bamboos can really only last about 2 years in a pot. they should never be allowed to dry out and don't like exposed sites. your should be able to divide or cut a chunk from the edge with soil attached and this should take of with no special tratment. A really good tip is not to tidy up any fallen leaves and to keep them as a mulch as the plant can then re-cycle the silica that's in the leaves to help with can formation. can you be more specific about what kind of bamboo it is as my answers are asuming it's a phylostachys of some kind