Agree with replacement recommendation.
The primary cause of warped rotors is the failur to properly torque the lug nuts. You may have a bad caliper, or you may not. I've rebuilt older Saab and Volvo calipers--nothing new as 93. Check the brake fluid--if it is nasty, you could have internal corrosion cause the caliper to malfunction, and it would be more logical to replace rather than try to rebuild. In that case, you might consider replacing as a set, but I never have done so. another cause for dragging calipers can be a bad brake line--the rubber will fail internally and the fluid won't return after braking is finished.

Do flush the brake fluid anyhow.