In replying in the 130115 MMD to Jonathan Holmes' posting about punches
and dies, Wallace Venable mentions that wear on the die plates is more
problematic than punch-pin wear and that quite a lot of die plate
surface has to be ground away to eliminate the rounding of the holes
and to restore sharpness to their edges.
The way the late Eddie Freyer coped with this problem was to use a
hardened punch with a donut-hole end slightly larger than the holes to
be repaired. He then used that punch, driven with a mallet, to swage
the hole slightly closed. Then he would re-drill the hole with a
reamer, restoring its size and recreating its edge sharpness.