cracked pump sprayer o-ring

I have one of those crappy $10 pump sprayers, a year or 2 old. I am using it to spray bleach outdoor cleaner on my composite decking (the cleaner works great). It has started leaking pressure once pumped up. The o-ring is has some cracks in it. Almost done with the job, dont wanna buy a new sprayer. Is there something I can put on the o-ring so it maintains a seal, like some kind of grease etc?