Hello sir, After your treatment is completed the hair will start to fall off within 2 to 3 weeks and new hair will regrow. And if you are concerned about how long your transplant will last, it will last for a lifetime. Also, I would like to tell you that there is nothing like preventing hair fall. Hair fall is a natural process in which few hairs will fall and then they will be replaced by new hair. By taking 4 times PRP a year you can minimize your hair fall but cannot completely prevent it. Moreover, it is very important to identify the hair loss phase. With the help of the dermatologist, you can identify your hair loss phase and according to that, the doctor will advise you about how many times you can take PRP in a year. For further assistance, you can contact on +91-8451897419. Or you can also connect with experts - Dermatologists in Lucknow. Hope my answer helps you.