I have a very old Christmas cactus. It used to bloom about 5 times a year. Due to moving and being left alone and having stems knocked off, over and underwatering....... It is still alive but the base of the stems are hard and brown. The tips are wilty. I transplanted what I could salvage into Miracle Grow Potting Soil. It is still very droopy after about 3 weeks. Can I do anything to save it?
Keep the faith! It's had a rough time and will take awhile to recover. Normally I don't feed a repotted plant until it shows signs of new growth. This lets it focus on root formation before the nitrogen tells it to push out leafy growth. It isn't a big deal. Did you know that it is possible to prune out old woody growth once the plant is healthy again? Like many shrubs, removing all woody growth helps the plant stay young and vigorous. Another way to continue an old keepsake plant is to take cuttings and start new plants. With Christmas cactus, this is particularly easy as you can nip off a small branch and just pop it in water. After roots form put it in potting soil. Here is an article that discusses general care and taking cuttings to start a new plant. https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/leaf-drop-on-christmas-cactus.htm