Sammy the extreme high heat is shortening the life of the heaters but there is another method that really reduces heater life span, not using soft start when the mold heats are turned on!! Check and most likely you'll find out the cold start or evaporation mode is disabled to start the mold sooner. When cold, some moisture will be in a heater and if the amount of current is too high, that moisture when released can short the heater internally. I'm sure the thermal shock hurts the heater elements as well; room temp one moment and red hot the next. Also I think that the mold might suffer from setting it in the press without pre-heating the hot runner.
The reason I asked about the water is there may be too much surface contact between the cold section of the mold and the hot runner. That's another reason why the heats are so high as the manifold is losing so much heat to the mold steel. I worked on an early manifold system that used the gas inside to transfer the heat around the entire system. We had an issue with too much heat transfer so we made insulating crush rings out of alternating pieces of brass and stainless steel. No more issues. Last possibility: when pulling the mold for change over, depending on mold design and water fittings it could be easy to not drain and blow out the water lines, disconnect tyem while under pressure and the cold water spray, run, drip, or soak onto the hot runner.
Rick.