There is no good way to reset Peak Demand on the PM800 series (or other Powerlogic Devices)
ION Enterprise or SPM7, PM800
This will reset the Power Min/Max Demand at the start of every month, based on when the 'Clock' determines that a new month has began--not '30 days elapsed'.
This process could be used for other values that should be reset at the start of every month as well, so long as it is a value that the register is accessible via ION Enterprise.
Clock-Based Reset Instructions.docx