Is there normally a lockout to prevent reverse thrust being commanded in flight (perhaps a weight on the main main wheels requirement)? If so, suppose a situation with a very close V1/VR, if an RTO was attempted and, with reverse thrust selected the aircraft did manage to become airborne would the lockouts enable/prevent the movement of (particulary mechanical) thrust leavers to be returned to a stowed/forward thrust position?
In the case of the 747, there is a reverse lockout that is actuated by the main landing gear tilt switches. So, the main gear would have to be fully off the ground to go into the flight (locked) mode.
I doubt many pilots would attempt an RTO after rotation with a single engine failure. Also, reverse thrust could NOT be selected until the main gear were on the ground again, so your question about restowing them is moot.