Why would I have to continually reset my hot tubs heater?
We inherited a a hot tub with a house purchase, it was probably 10 years old. After a few months of use, it would sometimes trip the GFCI breaker during use.

I opened the access panel on the hot tub and opened up the control box and the heater unit itself had some corrosion hear the pressure switch.

I removed the corroded heater and replaced it with an aftermarket heater, like the one below. This solved my GFCI problem.  FYI, you'd need to buy the pressure switch separately, heavy gauge wire, and be comfortable installing such a device yourself. Or, buy it and hire an electrician to install it.