I found some good info here:
Original equipment manufactured TPMS sensors have an estimated battery life of 5-12 years, with 7 years being the average. Tire pressure sensors are usually powered by 3-volt lithium ion battery or a 1.250-volt nickel metal hydride battery.
www.tpmsdirect.com
" Tire pressure monitoring sensors are usually powered by a 3-volt lithium ion battery. Some TPMS sensors use a 1.250-volt nickel metal hydride battery. The battery is encased in the sensor's molded plastic housing. A battery that is running low on or is depleted requires the replacement of the ENTIRE TPMS sensor assembly"
"The estimated life expectancy of an OE TPMS sensor is 5 to 12 years, with the average lifespan being 7 years. TPMS life expectancy is directly related to the number of radio frequency transmissions the sensors make. Driving habits greatly influence the number of RF transmissions a sensor makes in its lifetime. For example: sensors usually transmit when the vehicle is stopped and transmit more often when in motion. Maintaining a constant speed, such as when you're on a highway, reduces the demand on TPMS sensors and allow the sensors to transmit less often. Drivers who often find themselves driving in start-and-stop type traffic will have a greater impact on the vehicles tire pressure monitoring sensors. Weather can also have an impact on tire pressure sensor battery life. Cold conditions allow batteries to last longer. Warmer conditions take more of a toll on TPMS battery life."
So it would seem that this is a wear item that could require replacement at some point. So maybe its not a bad idea to just replace them all. Or get rid of them. Decisions Decsions.
One thing to note is that I am pretty sure the Procal that AEV includes in the lift kit can be used to change the TPMS warning pressure. So if I set my warning at 20psi, I would only have a warning ligt when aired down off road or have a serious problem