Some TMNT stuff really isn't for little kids.
After the Turtles were transported to Batman's dimension, April and Harold Lilja worked together to keep a lock on the Turtles' location. When Casey Jones returned without them, April accompanied him on a risky interdimensional journey to rescue the Turtles.
After Bane came to Gotham, April spent a great deal of time capturing footage of him on her phone, allowing Batman to discern how much Venom was left in Bane's tank. She also comforted Donatello as he struggled with guilt and feelings of worthlessness, before convincing him to referee a fight between Raphael and Robin.
While Batman, Robin, Splinter and the Turtles all attempted to take down Bane, April was left to tinker with an interdimensional portal in the lair. When a critically injured Splinter was brought back to the lair, she helped care for him, and argued against Donatello's reckless idea to use Venom to even the odds.
A few days later, she successfully made contact with Batgirl, arranging to open the portal so that Raphael could bring Splinter to the Lazarus Pit to be healed.
When the final assault was made on Liberty Island, April was put in charge of driving the Turtle Van off the ferry, and launching her friends into the middle of the fray. Having done so, she began freeing the captive humans imprisoned on the island, allowing them to head back to the ferries.