There is certainly no need to replace them just because of play or mileage. As said, it is the noise or lack of it that counts. Mine are perfect on 288,000 miles. I adjusted them once, at about 200,000 I think, and filled the cap with new grease about every 50,000.
My technique is:
Leave the wheel on if possible, and
1) remove split pin and tighten nut fully. This will eliminate all bearing play, so you can feel whether anything else is causing it.
2)Slacken nut until you can just, but only just, detect some play when you grip the wheel top to bottom.
3) Refit pin in an appropriate hole (or better use a NEW pin!)
4) Repack cup with grease.

I have owned or serviced dozens of cars and quite a few 240s. In my experience greased and adjusted front wheel bearings never wear out. (rash boast!)