From Paizo itself there is nothing mundane linked with heal skill that can reattach lost limbs, or at least i never seen something like that related to this skill:
Anyway keep in mind that there is nothing in the rules that can severe your arms or legs (not in combat at least). Usually these are houserules or GM's decisions related with campaign or character story.
Maybe there is something really specific that can cause your character a lost limb but I'm pretty sure is a magical meaning and not a mundane one; in the same way to reattach a lost limb, you need magic (regeneration for example).
Ofcourse, if you want, nothing can stop you to insert something like "Reattach Limbs" in the heal skill and give this ability a 30 DC or something like that.
Reattach Limbs DC 30 (hand/foot) DC 35 (arm) 40 (leg)
Thanks to your surgery expertise you are capable of reattach lost
limbs. To reattach someone limbs, the limb can not be severed for more
than an hour before the surgical operation begins and you must be
trained in the heal skill. The operation take 4 hours for a hand or
foot and 8 hours for an arm or leg and you can't operate alone but
only with, at least, one support trained in the heal skill. The character who undergoes the surgical practice must succed a fortitude check at the end of the surgery equal to 15 (hand/foot) | 20 (arm) | 25 (leg). If the character fails the fortitude check he dies from blood loss.