I just had a not viable pregnancy after ivf treatment. what can i do to get a better result , since i'll be using my frozen embryos.

A matter of chance: Most non viable pregnancies are the result of an embryo that is genetically abnormal. The majority of embryos are abnormal and most of these will declare themselves by not growing or not implanting. This is particularly pronounced as you get older. Other than using an egg donor, your best bet is try again with frozen or with fresh embryos.