Q: Chances of repairing a cracked exhaust manifold vs replacing?

If you are wanting to fix a crack in an exhaust manifold rather than replacing it, you would need to clean the manifold up, weld the crack, and clean the surface up to a true connection as the manifold will distort when it gets very hot during the welding process. The best move would be to replace the manifold with a non cracked manifold. If you need further assistance with your exhaust leak, then seek out a professional, such as one from Your Mechanic, to help you.