Not a good way, but you could query PowerStrip for such information (bad since requires 3rd party application and wont work with Nvidia > 7xxxx series). Reading from HW would be the best way, but I guess you wont want to develop another PowerStrip (and not to be able to read from newer Nvidia GPUs).
A good solution could be a reclock exposed com on .net library to query the exactly refresh used by reclock itself.
I'll try to ask this to Jong or James (reclock devs team). (better if reclock is not necessary indeed)