The safest thing to do is to buy the original off the Internet. If that's not practical, consider the following.

Most NEC projectors use NEC1 protocol, device 24.233 or 24.247. I don't know about the NP100, however. Some of the universal remotes which can provide this protocol are listed at www.hifi-remote.com/jp1/lookup/.  Click on Protocol Search, then choose NEC1, and enter 24 as Device 1, and click on search.  Look for TV 0497 and TV 0603, and click the far right link (0497 has 32 as the link).  That gives you a list of remotes which possibly have the capability to control the NP100.  If you go this route, I would try to find a remote which has both 233 and 247.  In the list of remotes, 15-xxx is a Radio Shack remote, and URC-xxxx is a OneForAll brand.  Atlas and Comcast are cable companies.

There's no guarentee, but it will probably work.  If a few buttons don't provide the correct functions, you can individually program each button.  We can tell you how to do that.