Supposed to loose 1/2 brightness in 10 years I believe. Radioactivity (very very small amount) is what is going on for the brightness you see (that was poorly said).
I like mine for - spotting my flashlight on bedside table in hotel, on my keys so I can see them hanging up in dark or buried in my bag.
I don't think there is anything you can do to extend life. The Norland 61 that is typically used can be softened with a heat gun if you want to change them out.