The official Daredevil Twitter account released teaser images for Season 2 which suggests both Gladiator and possibly an updated and/or different Daredevil costume, as well as Elektra.
The image includes a saw blade with the initials of Melvin Potter, who appeared in Season 1. Potter is also known as the Gladiator and is a friend/foe to Daredevil having created his costume.
We also see sketmatics for an altered Daredevil costume, which could either be an update for the cowl or maybe an earlier version/design.
The second image features the weapon of Elektra, who will be played by Elodie Yung.