Sounds like leaking seals need to be replaced with seals made to handle higher temp's and a lubricating fluid change done. I'm not sure what type of equipment you are working on but you may want to check with the manufacturer and see if they make different seals for them, they may have started making different seals since the equipment was purchased. You could also try aftermarket and see if someone makes higher temp seals.
Depending on what type of fluid you are using you could try using a thicker/higher viscosity oil. Other than that I don't know what you could do but use a viscosity improver to try to thicken up the current fluid at high temp. Something like
800 Polymer might work if the leaks are not to bad. If nothing else it would slow them down.