Sometimes when you watch a TV series you like, on the second or third season you have a certain nostalgia for the feeling you had when the series just started. Those few episodes, or maybe the whole first season was somehow different.
If the series is successful in its later seasons, you can create new episodes in the same style, atmosphere and corresponding to the plot lines that existed in the first season. You can insert them between other already well-known episodes to expand on them.