Hi Talino
Not being an expert on sculpting but a keen figure painter and used to solving these kind of minor problems I would suggest this.
I would score with a scalpel the smooth area that you were left with to provide a "key" to then accept an amount of magic scupt or something similar then using a cocktail stick or as I usually do a dental tool which you can easily obtain off the "net" sculp the hair using the original hair that is still on the figure as a guide you can then easily blend the new "hair" into the original After drying and spraying with undercoat you will not be able to tell the difference
Try and have a play at it and good luck
Hope this helps
John (Normo)