Best to change TPMS sensors before the battery dies. Most shops can transfer information from old sensor to new sensor. Once the battery dies this can no longer be done. You have to then program sensor from scratch.
I got lucky my tire shop took my car to another shop that had the old Chrysler DRB to perform this for my one dead sensor. I do not put on many miles, My tires will be changed because of age. I will change my sensors at that point also before batteries die.