Interesting question, one that all of us have likely asked ourselves. I too, have been pondering the question, as I had a thriving nano reef will corals all grown out, and then, after deciding to switch salts, things went down hill. Long story short, got a bat batch of Neo Marine (Selenium was off the chart), and after months of water changes, corals started checking out. I needed to do a big water change, and thought that I would use the opportunity to facilitate a resurrection. After an 80% water change, a thoroughly cleaned my sump, and a relocated the aquarium, I though I was on the road to recovery. ICP numbers were better, but I ended up getting bryopsis, hair algae, and dino. (Later discovered that Neo Marine was putting unwanted PO3 in my aquarium with every water change >0.06). I have changed to a new salt again, beaten bryopsis with fluconazole, purged my sump of hair algae and treated 75% of my live rock with peroxide. However, I still have dino and my some of my corals are still not on the road to recovery. On Reefbum's advice, I am hoping a marco algae reactor and time will help me beat the dino and bring this resurection to a successful conclusion.
As you can imagine, it has been a long and frustrating struggle. I could have worked to make an upcoming upgrade happen sooner and thereby restarted in a new system. Live rock has been curing since January and the essentials for the upgrade have been bought. But, I guess the question you need to ask yourself is, will the restart lead to the same result in the future? If not, then restart. However, perseverance is something that everyone seems to preach in this hobby. Knowledge comes from it and is why a resurrection may be the way to go. Honestly, that is what I have perceived from all the threads and videos that I have read and watched. Besides, however much you put into making your reef better will only benefit you as a reefer and isn't that the ultimate goal of this hobby--learning to master the difficult, and at times the seemingly impossible, so that a living and vibrant ecosystem can thrive in our homes.