How can serrated knives be sharpened, without the serration being eroded? This post recommends having serrated knives sharpened by professionals, and not an amateur. I ask about whetstones, steel rod, and pull-through sharpeners.

But wouldn't sharpening efface and remove the serration? Or can the professional recreate the serration? Here's my knife that needs sharpening, where I use these knife terms:
They can't really. The purpose of knives with microserration like in the one shown are as an alternative for people who are looking for knives that won't require upkeep.

Knives with a much wider serration can be sharpened professionally but it can be tricky.