In small saucepan place apricots and water and allow to stand, covered, 2 hours. Simmer 20 minutes on very low heat, tightly covered or until apricots are soft. Puree along with any remaining liquid in a food processor fitted with a steel blade. Add Grand Marnier, lemon juice and sugar, mix with several on-off turns. If desired, for a sweeter filling add more sugar.
Fill cupcake.