Any repairs would have to be made in accordance to the original construction methods, materials and plans as far as possible. Given the extremes that are gone to to patch up mediaeval cathedrals, some Victorian Gothic Monstrosity should be fairly easy to do. After all, it’s an iron frame with stone cladding.
As a building, I’ve never really liked it - too lumpy and not old enough to carry the gothic styling. IMHO it would be better to flatten the thing, and rethink the “cross the floor at a swords length” approach to how government works anyway. It’s currently a bear pit and is far too up it’s own arse for any good other than as a historical curiosity.