Hi Justin,
The P6015A does not use a dielectric fluid, instead it uses a silicone based insulator that does not need to be replaced/refilled.
The P6015 (non-letter), does use a dielectric fluid that can be refilled, more information is available here:
https://w140.com/tekwiki/wiki/P6015
Please do note that R-114 has been a banned product for over 30 years and the probe can still be used (although derated, as specified in the manual) without the fluid.
