Probably rootbound, so it is water deprived, water can't penetrate into rootball. Soak rootball in pail of water 30 minutes. Ruff up rootball some, and put her to next size pot, with just moistened soil, AND ! Wait a week before watering. 👍👍
Trim any bad and old leafs off.
SHE'LL BE BACK ! Besides ! She doesn't look bad, at all ! 👍😎😎😎