It is no longer necessary to obtain a license to permit dancing. However, a business with dancing falls under Use Group 12 (as opposed to an eating/drinking establishment, which is Use Group 6). Unless a specific location is grandfathered with a C of O that permits dancing (such as Webster Hall and Pyramid in East Village), zoning in CB 3 that permits dancing is generally C 4 or C 6 general commercial districts. Below is information from the NYC website for cabaret license. The license is no longer required, but the zoning and C of O requirements remain the same. Additionally, if the method of operation of the business on the original SLA license does not provide for dancing, the business must apply for an change of method of operation to allow dancing at the establishment.
Obtain a copy of the Certificate of Occupancy, Temporary Certificate of Occupancy (expiring no less than 30 days after the submission of this application), or Letter of No Objection from the Department of Buildings (DOB) confirming that the business' premises is suitable for the business. If submitting a Certificate of Occupancy or Temporary Certificate of Occupancy, it must be the most current version and show approval of the premises for "Use Group 12" and "Cabaret" or "Eating and drinking establishment without restriction on entertainment."