Rachel Hall has been in the hospital since the crash at the intersection of North Park Avenue and Diamond Street in North Philadelphia.
Her mother, Kathy Hall, said in the post "Doctors will be trying to awaken Rachel. I feel she is moving in the right direction."
The post went on to read: "Rachel has a tracheal tube in her neck to assist with her breathing and a feeding tube in her stomach. She is not coherent, cannot speak or communicate which is extremely frustrating."
"Rachel's progress is very slow."
Read more at the Rachel Hall - Temple Strong Facebook page.
Robert Roberts, 18, is accused of hitting Hall with his car as she was riding her mountain bike, then fleeing the scene.
Police say they obtained surveillance video of Hall riding through a stop sign when she was struck.
Roberts, who only had a learners permit, told investigators he panicked and fled. But he and his family came forward to police less than 12 hours later, turning over the striking vehicle.
Police say had Roberts stayed at the scene he probably would not be facing charges for the crash, though would have faced a permit violation for not having someone over 21 in the car at the time.