"but his sheveth shall he give": I might think, forever (i.e., for life-long disability.) It is, therefore, written "and heal shall he heal" (i.e., he pays) sheveth only for so long as it takes for the wound to heal.
If the Torah Envisions the Wound Being Healed, Then the Compensation
Mekhilta Tractate Nezikin 6:17