All reactive resin balls will see some loss of performance over time. Some hold up longer than others, but even the most durable cover stocks still need some routine maintenance.
How much and how often depends on countless variables, which is why it's so important for the serious bowler to learn how to read ball reaction. When the ball is no longer reading friction how you like it, it's time for that maintenance.
A ball used by the most dedicated person, who cleans it after each set, will still likely be oil-soaked after 60-80 games. That time span shortens dramatically for those who don't keep it clean. Resurfacing the cover should go hand-in-hand with the oil extraction process.
Today's balls are usually finished with a more coarse grit (maybe 500), followed by 2000, 4000, or even polish. The reason for the underlying grit, the coarse one, is to help the ball displace the oil more effectively. As we use the ball that surface smooths out, so to speak. The microscopic "peaks and valleys" disappear, and the ball doesn't traction as well as when it was new.
This can take place amazingly fast when the bowler is on a high friction surface. And the oil absorption rate is higher if the bowler plays in the more slick portion of the lane.
So, to summarize. I think it's crucial to clean today's equipment before the ball goes into the bag. Frankly, some of that lane oil has started soaking into the cover in the time between the pinsetter and the ball return. Wipe it off between shots, clean it as soon as you can, and still do the regular routine maintenance, and your chances of your ball lasting waaaaaaaaay longer go up.
Many of you don't have a spinner, which is fine. Not all spinners are created equally. And it takes years of experience and experimenting to become adept at changing/tweaking ball surfaces to enhance pin carry. Find a trusted pro shop who will really listen to the issues you're having and you'll become sold that some expertise in this area can go a long way.