Arrow, The Flash, Supernatural and The 100 are among the shows that CW has already renewed for next season. The Vampire Diaries will have a 7th season while it's spin-off , The Originals will go for its 3rd. Reign will be entering its 3rd season while Supernatural hits its 11th season. The Flash zips forward to its second season while Arrow shoots for the 4th.
This is fairly early for a network to renew all its shows like this and CW is obviously happy with their ratings.