Combine raspberries, lime juice, and sugar in a high-powered blender. Blend until smooth.
Strain through a fine mesh strainer into a large pitcher. Use the back of a wooden spoon to press the mixture through. Discard the seeds and pulp.
Add ice to individual glasses and pour the raspberry limeade on top. If serving this drink immediately, stir in the sparkling limeade and whisk to combine. If you aren't going to finish this drink in the same day, add the sparkling limeade to individual cups as they're served.
If desired, garnish with fresh raspberries and lime wedges.