In a medium saucepan, combine the berries, sugar and lemon juice, and heat over medium-heat. Bring to boiling; reduce heat. Simmer, uncovered, for 10 to 12 minutes or until thickened. Stir and mash, while heating. Transfer to a bowl. Cover and chill for 2 hours. Place in the refrigerator to speed things up.
Spray the interior of 4 rocket pop molds lightly with nonstick spray. Alternate layers of yogurt and raspberry puree in the molds until you've used up all of the ingredients. Add the sticks on top, and freeze until completely frozen (this is best to do overnight).
To serve, run warm water on the outside of the popsicle molds until the popsicles slide out easily.