Stush I had the same problem with keeping campfire alive. I am amazed at this one that it is growing like crazy now for two years and I now have it in a couple of pots. You know I like to do combo pots and the color is a good boost to a combo pot when I want a lot of color.
I did not realize why I lost it until I read the description..........
"It deteriorates after flowering and young shoots soon take the place of the older plants"
What I did last year is when it flowered I rooted all the leaves on the flowering stem and I scattered the seeds from the flower on the soil and now I have a lot of them.
What happened to your Variegated plant is they are weak. If they are damaged the green takes over. I cannot let any of my variegated plants suffer like any of the other colors. Our climate does not permit plants to grow outside long enough to get the strength of the sun and outdoor conditions they need. They really have to be babied.