As the previous poster said, those aren't decals, they're screened. Furthermore, the art appears to all still be there. The clear has chipped around the insert, probably because the insert is slightly raised. Why are you talking about replacing them!? That would be 50x the amount of work.
If the inserts are raising, we need to get them back down. Easiest way is a hair dryer underneath the insert, on high, for about 3 minutes or until hot to the touch. Don't worry, a hair dryer won't get hot enough to melt the insert... a heat gun will though in a matter of seconds, so don't use a heat gun! Then take a wooden block bigger than the insert, place it on top of the insert, and use a rubber mallet to tap it back down. Repeat this until the insert is flush with the playfield. Once flush, take some water thin super glue and, from underneath the playfield, place a drop or two here and there where the insert meets the wood. Capillary action will take effect and suck the glue in and bond the insert to the wood. Now that sucker won't be going anywhere anytime soon.
Then I'd touchup the black border with black water acrylic paint. Going to take a few coats or light will shine through. Then I'd seal it in and rebuild the missing clear little by little with either varathane ,or water thin super glue, from a pipette.
Total time to do this job? Probably 2 hours. If done properly, nobody would ever know something was amiss.