Have you fertilized your Josephine with a good rose food at the end of winter and added manure around the root base ? These both help to build strong blooms and strong plants. A strong plant is MUCH less susceptible to wilt. Don't worry about the wilt. These wilt problems can strike just about ANY group 2 clematis, but older plants seem to have MUCH less of a problem with this fungus. You may or may not ever see wilt on her again, who knows. Cutting off the dead stems now will leave enough time to sprout new vines for next year's flowers.
Suzy