In a small saucepan, sprinkle gelatin over 1 cup cold grape juice; let stand 1 minute. Heat over low heat, stirring until gelatin is dissolved. Stir in sugar. Remove from heat; stir in remaining grape juice. Cool to room temperature.
Transfer gelatin mixture to a large bowl. Slowly stir in champagne. Pour half of champagne mixture into eight champagne or parfait glasses. Add 1 strawberry to each glass. Refrigerate glasses and remaining gelatin mixture until almost set, about 1 hour.
Place reserved gelatin mixture in a blender; cover and process until foamy. Pour into glasses. Chill until set, about 3 hours.