My daughter Misses her preschool friend?

My daughter is 3 yrs old she has a friend from Preschool that she talks about non stop, and through out the yr I got some what close with the little girls mother and it is now summer time and she told me to call and we would get the girls together. I have called several times and have not heard back. My daughter is crying over how much she misses her little friend what should I do?