Auto change CV in Manual Mode PID

I have a PID that always runs In manual mode, due to having an unstable Analog input. At times in my process I would like to change the CV of the PID downward automatically by a specific amount, followed by a gradual climb back up to the original CV setpoint. Using upcount/downcount feature of the PID doesnt acheive the return to the specific setpoint I need to control the process.I use GE fanuc 90-30 PLCs, Versa-pro, and Cimplicity HMI. What is the best way to accomplish this?