Bro, fishes seem better is not a sign u have killed ich. If u have done copper for 4 weeks then u can remove the copper. Use carbon, polyfilter and many many water changes. What's ur intention in adding cured rocks? Any copper in the water will just kill the newly added cured LRs which could lead to ammonia spike if u added alot.
If u want to add corals again, it would take a few weeks to months of changing water and carbon to ensure the LR is not leeching copper back to the system.