Yes you can use a higher category during the circling. You have to use the higher MDA and need the increased visibility.
There is noting stopping a Cat A aircraft using Cat C minima for a circling approach since all that happens by raising the minima to the CAT C ones is that the area within which the aircraft must remain gets bigger.
So if as you found that due icing or due configuration limitations etc you have to use a speed higher than 135 for your CAT B aircraft all you have to do is use the higher minima for a CAT C so as to increase the size of the circling area to accomodate your higher speed.
What you must not do is fly a CAT C aircraft and say that "today we are so light that we can fly at 135 knots during the circle so we will use the CAT B minima". That is totally against the rules.