I agree with clowns101. I just have to think a bit more light "might" help. The recent picture still shows some color to the foot and the tentacled are a white with colored tips. If it has not shrunk to a hopeless state I would think it has "some" potential to grow. I personally would not give up until it starts to turn brown, totally shrunken, rotten stinking blob.
I dose Kent Marine Essential Elements, Iodide, and Strontium & Molybdenum every Wednesday. I do a 10% water change once a week with Instant Ocean Reef Crystals. I like the new product by Brightwell Aquatics Zooplantos - Large (500-2,000 Microns) although I am finishing a half gallon of Kent Marine Zooplex 800 microns. Zooplanton is a larger coral food as well as the Microvert from Kent Marine I use weekly for corals, anemones, etc.
You could add something like a bacterial additive weekly with water changes off and on to help with water quality. Seachem has a good product I have used called with your called Stability although I have switched to Colonize by DRS. F & S for a better price. You can does the entire tank with Stability and not just you replacement water.
I also use Seach Reef Buffer.
I now have two specimens listed as expert level by Drs. Foster and Smith, an Indo-Pacific Regal Angelfish and the new Heteractis Magnifica and they do not seem bothered by these additives.
I used to use Amquel Plus to remove chlorine etc. with water changes and does the entire tank and switched to Drs. F & S Stabilize for the price.