My guess would be you would have to go in and replace it with some kind of replacement lens from china. A quick Amazon search pulls up this one. Not sure if it is the right one.

You may also need a new glass screen after you get the original off, but you may be able to use the original if you clean off all of the UV glue well enough, assuming you don't break it in the process of removal. I would probably just order another screen as well if I were going to dig in.

With that being said, I would probably look into what services Samsung provides in terms of repair, as I would not trust myself enough to start tinkering around on my Note 5, voiding the warranty.