IF you actually need to replace the rings, a 22-32-44 or 24-34-42 or similar combinations should work fine with possibly just a slight FDER adjustment. If you stick with the 42T large ring, you likely wouldn't need to.
Going to a 48T large ring would require a new FDER for decent shifting, although you could probably make the old one still shift with a decrease in precision.

I suggest you look at the rings on a NEW bike. You'll see they look well worn to the untrained.
FBinNY gave you good advice for checking them. If they don't skip, they're good.