My 4 year old wants to read the same picture story book again and again, how do I vary it ??

Most children want to read a storybook or watch a tv show again and again Coz they like to know what is going on already. They want to be in control of the things around them so as to make them feel good. Read https://en.m.wikipedia.org/wiki/Erikson%27s_stages_of_psychosocial_development for more info.