Screenwriting : Formatting question for introducing characters in series episodes by April Spiller

Hello, wise Yoda-like writers of the internet. I have a quick question. I am working on a series, and I have a question about introducing characters. In the first episode of a season, I am introducing them like in any other screenplay, with their descriptions. But... in subsequent episodes (episode 2 and so on) within a season, do you have to introduce them again if they were already introduced in the first episode? Would you just assume that the same person is playing the character and that they haven't changed from one episode to the next?