Good question - I would create three avenues for your Volleyball recruiting communication:
1. Your initial outreach to schools/programs which fit the broad parameters of your VolleyPSA's academic and volleyball goals.
2. Programs which are in consistent email contact with your PSA.
3. Programs which have not responded, but are of interest to your PSA.
With these three categories, you will have a different interaction plan. With group 1, this should be a low key, but consistent effort to reach out to new programs with information about your daughter. Could be one program a week or 20, depending on her parameters.
Group 2, continue your current efforts, as they seem to be working.
Group 3, dial it back to one email update every 2 weeks or so.
Remember that many times coaches can just be forgetful or overworked during a certain segment of the year. I found that my busiest time of being a coach was right now, in April. We are in our heaviest recruiting cycle, we are trying to train our team during the non-traditional spring season, we are traveling for spring season matches, we are hosting visits from PSA's, and let's not forget the 10 thousand pieces of paper we must fill out to document everything. Too many volleyball programs don't have a second assistant, much less a director of operations or access to a secretary.
Unless a program has responded to you by saying "we are done recruiting", I would keep them on the contact list, but just not as often. The rationale is that recruiting needs are constantly in flux in today's collegiate volleyball environment, and many times the athlete which stays in some form of communication may be in the best position if a program 're-starts' the efforts for a particular year.
I would not call group number 1 or group number 3; email is your best avenue. Calling is best for programs with who you are in active communication with, not those you are reaching out to.
My compliments to your efforts and continue the communications.