A technician can
1. put in new, slightly larger tuning pins, which will make the tuning hold better.
2. ease up the action in different ways, or replace it with new action parts.
3. see 2
4. adjust the pedal, adjust the dampers, or replace them with new dampers
If the tuning block (where all the tuning pins are sitting) is cracked, there's virtually nothing he can do.
If the metal frame is cracked, same. He can't do anything.
If the soundboard and bridges are cracked, he can repair it, but it's a big job.
The ideal thing to do is make sure the tuning block and iron frame are intact, and that the soundboard and bridges are at least repairable, and then install new tuning pins, new strings, new action parts. It will cost a bit, but your piano could become like a new one and last you another 50 years.