Before I bought in bulk and when I was paying a lot for my pieces, I would constantly add bits using see-thru thread, patching and repairing.
I'd cut out the bare area and put a piece of spare in its place from underneath, pulling the hairs through the hole and stitching it down.
It works to a degree but you have to be careful brushing & combing, not to catch the threads.
Its not until you get a brand new piece that you realise what a pain your old patched up one was.