The flight instructor (CFI) and student pilot had completed the first leg of a night cross country flight and were departing back to their home airport. During the takeoff roll, a deer ran onto the runway, colliding with the airplane's right wing. The CFI assumed control of the airplane from the student and continued the takeoff, as inadequate runway distance remained to abort. Once airborne, the CFI did not note any flight control abnormalities, and elected to continue to the destination, where he landed the airplane without incident. Postaccident examination revealed substantial damage to the right wing.