There are many reasons for a dying ZZ plant after repotting, and the most common one is root rot. Root rot results from overwatering. Prevent this issue by watering your ZZ plant once every 2-3 weeks, and check that the top-inch soil is dry before watering again. A ZZ plant might look like it's dying while going through transplant shock after repotting, such as drooping or falling stems, but it will soon recover with proper care.