"and heal shall he heal": (Whence do I derive that if) he were healed once, and then healed again, even four or five times, he is liable (if necessary) to keep on healing him? If growths sprouted because of the wound around the wound, he is liable to heal him. If not because of the wound, he is not liable. The Torah states: "but his sheveth shall he give, and heal shall he heal." Just as sheveth, because of the wound, so, ripui, because of the wound.
The Torah Doubles the Word Heal in Nezikin
Mekhilta Tractate Nezikin 6:19