In my zone I'd cut it back again now but I'm not sure if there is enough time in yours to cut them twice.

Look at the vines and find where they have a viable leaf axil as low to the ground as you find..might be 2nd or 3rd from the soil and prune above it and fertilize..you should not only get more blooms later on in late summer/ early fall but also more vines might emerge from the soil...Jeanne

Thank you....did you mean to trim just one vine or both?

Both, Etoile Violette is a type III which should be hard pruned every year in early spring/late winter and benefits from additional prunings when young.

prune all vines on the clematis ...Jeanne