Answer: Yes. If you suspect that a cemetery is abandoned or neglected, contact the Office of State Archaeologist. If the cemetery in question is in fact unrecorded, then one of these state agencies typically is the authority on granting permission to work within the cemetery. Regardless, you still will have to request permission from the land owner to access the cemetery.
[note: The above answer comes directly from the Wisconsin Historical Society - Historic Preservation Division. If you're not cleaning a gravestone in WI, check with the state historic preservation office in your state because similar rules will apply]