The Penguins do not have any unrestricted free agents come July in which they need to worry about resigning. They do have multiple restricted free agents in which I would look into resigning sooner than later. Rust, Sprong, JSD, and Jarry are all on the market July first.
In order to attain one of the defenseman mentioned above, the Penguins could look into moving Conor Sheary. Moving Sheary would ease three million dollars off of their salary cap. Another player in which they could possibly move is Carl Hagelin, who makes four million a year. Hagelin has been a good player and penalty killer for the Penguins. Come the start of next season, in order to make it deeper into the playoffs, the Penguins need to shape up their defense to be solid contenders.