I'm amazed that you have had flex PVC last 30 years! That's a record, in my experience.

While there are some methods of snaking new pipes down old holes, I doubt they'd be practical in your situation. I haven't seen photos or details, so I can only guess, but my guess is, 'Yes, you'll have to dig up concrete, if it's over the points where you connect'.

You often CAN cut straight across the deck to the skimmers, and run the rest of the piping outside the deck. That may work for you.