It always happens. In the life of each of us; in the life of the Church; in the life of religious orders and communities. There are the saints, the ones who take the Gospel to the max...and then it falls off. The ideal is there and lived for and given...and then people get tired.
And so God begins the process again.
In most cases with religious families, the charism given is still needed for the Church. It's just that those who are living it are...lax or less than the ideal. Sometimes there is scandal. More often, they just lose their edge. So, he gives another person the grace of the vocation, and the order or the community grows again as sanctity is caught and the light given originally flames forth.
This happened to the Benedictine order a number of times. One of the most enduring renewals was that of Citeaux, the original home of the Cistercians. The order was founded in 1098 with the desire of following the Benedictine Rule more carefully. The first three abbots: Robert of Molesme, Alberic of Citeaux and Stephen Harding began the reform, which emphasized self-sufficiency and manual labor. Bernard of Clairvaux joined this monastery early in the 1100's and brought with him thirty companions. The order grew explosively at that time.
There are Cistercian nuns also, women drawn to the austere life of the Rule. And continue to do so even today. To live wholly for God according to the Rule of Benedict in a stricter form.