This is a common question on a bunch of these boards - ball death.
To answer this question directly I have not noticed ball death with my Agent that I have bowled around 100 games.
IMO ball death simply means that the cover has been altered in some way that you can no longer get the intended reaction. This usually happens from either a specific alteration you have made (sanding, polishing, etc.) or from lane conditioner seeping into the ball. The
I clean my equipment on a regular basis with one of the Storm cleaners - in this case reacta shine. These cleaners significantly slow down the damage caused by lane conditioner seepage but they do not eliminate it. Other vendors have similar cleaners and I am sure they do virtually the same thing.
Another way to prolong ball life is resurfacing. Be careful though, make sure the resurface is what you want - sanded and finished to the specs you expect. Any change at all can cause a change in reaction and cause the owner to declare 'ball death'.
The last way that I know if is that there are machines out there that extract conditioner by heating the ball to about 140-150 degrees. I don't have enough experience with these to say whether or not they work.
The only ball I have ever owned that I would claim 'ball death' to was the Super Charge - but that was after 3 resurfaces, 250+ games, and 2 years.