Is it possible to get mono more than once?

Married to it. Mononucleosis caused by ebv (epstein bar virus) some times also by CMV (cytomeglovirus) once infected virus stays in the body rest of the life, so married to it and rarely get a divorce!
Yes. Mono is caused by the ebv virus. Once a person catches ebv, it seems to stay in one's body, and can re-activate to cause mono-like symptoms more than once. Staying healthy & happy, eating a balanced diet, and getting reasonable exercise, etc... May help keep one's immune system in top shape, to keep the ebv virus suppressed. Occasionally, other germs can cause a "mono-like" illness.