IANAL and I am not familiar with NYPD protocol, plus without knowing all the details of the case (not to be rude, but I don't really care to know), it is hard to give a specific answer. Some ideas you may try though:
1. Request the detective's supervisor
2. Contact the victim advocate or an ombudsman for the department
3. Contact the district attorney's office and ask options
4. Speak to an attorney and get the attorney to put pressure on the police and/or city
If they haven't done anything for 6 months as you say, there is something else going on. The individual could be part of a bigger criminal investigation that they have not shared with you. Or you are just stuck in a legal limbo of sorts. There could be some gray area around how the individual's information was found using that software that prohibits the police from acting on it. They could have also filed paperwork to investigate further and it is stuck in some bureaucratic red tape or on some desk somewhere. You are probably better off just speaking with an attorney and letting them handle it.
Now if it were me, I would probably just cut my losses and chalk it up. Unfortunately in the big scheme of NYPD, a stolen laptop is probably a non-priority case and collecting dust somewhere. As frustrating as that sounds, by the time you hire an attorney, waste your time pressing forward, etc.. you could have purchased a new laptop and moved on.
Sorry I can't be much more help. I have been there myself. My house was robbed about 15 years ago and I had a laptop and desktop stolen. Was able to track it down, but still took close to 2 years before it was finally returned to me. By then it was pretty much worthless and anything of mine that had been on them was long gone.