Transfer gelatin mixture to a small saucepan. Add sugar and cook over moderate heat, stirring, until sugar is dissolved. Pour mixture into a bowl and set bowl in a larger bowl of ice and cold water, stirring mixture gently until it is cold and slightly thickened but not set. Stir in pomegranate seeds and spoon topping onto chilled cheesecake. Chill cake until topping is set, about 1 hour. Remove side of pan and serve chilled.