Is it true as some Pastor's teach, once saved and repented, one needs not to repent anymore?

Great, good question and answer. Also, repent does not mean sorry, It means change . We change from being a lawbreaker, to a law keeper. God no more expects us to sin , but if we do, by accident as it were, we have an advocate ....1Jn_2:1  My little children, these things write I unto you, that ye sin not. And IF any man sin, we have an advocate with the Father, Jesus Christ the righteous: .. Not when we sin IF. "When" refers to expected behavior , like when you fast, or when you pray. as we do as Christians. God does not expect us to continue to sin after we have repented.