The life of the laser depends on how long the laser diode lasts.
Laser diodes on average have a shelf life of about 3 to 4 years and designed to operate well over 5000 hours.
Once it expires, the laser will no longer function.
Diodes degrade naturally over time due to oxidization, temperature, light output and moisture even if it's not in use.
These cannot be replaced without fully disassembling the laser, considering the parts and labor, buying a new one would be a better option.