Refreshing is re-cutting the old grooves and tops of the lands, if needed, using lead laps cast in the bore.
I have a few .172" groove diameter barrels, with .002" rifling depth. They are easily tested for rate of twist, using a tight patch on a rod that doesn't even have a rotating handle.
I am having a difficult time understanding how you cannot measure the rifling twist on your barrel, if the rifling has not been removed to start with. A lubricated tight patch on a jag
should work.
As to measuring, is it due to an odd number of lands? This should be evident looking through the barrel, or on the cerosafe casting.