Hot or dead pixels are pretty much a fact of digital life on all digital cameras, and will often occur on longer exposures especially. When the camera is new, they are mapped out at the factory, but more will usually develop given enough time. Rumor has it that using Live View on a D300 or D3 might fix the problem - but that won't help you on your D200, which doesn't have that feature AFAIK.
AFAIK, there is no Nikon-specific software that allows you to go into your camera's firmware and re-map the sensor yourself - you'd have to send it to Nikon and have them do it (I've done this and it worked great - but mine was under warranty). You could retouch them with the auto-retouch brush in Capture NX/NX2 and set it up as a batch process to do an entire folder, or you could set up an action in Photoshop to clone it out. You may well find that it's not intrusive enough to bother with in most situations.