Not really sure. The badly damaged anemones I've nursed back to health have had at least part of their mouth/digestive tract remaining, and once their mouth fully healed, I was able to provide supplemental feeding of meaty food that I believe helped them recover. Without a mouth/digestive tract, an anemone will have to use a large amount of energy to rebuild/regrow that, and I don't know if just the remaining zooxanthellae in the base (without the additional surface area of the tentacles) will be enough to power this regrowth. It may, and you may end up with a much smaller anemone. Good luck!
Kevin