I don't know Dejan's use-case, but we frequently want to visualize
short snippets of sensor data repeatedly. Although rviz seems to
handle that correctly, rosbag does not provide an option to repeat the
data. That would be handy, but (as Dan mentioned) respawning rosbag or
calling it in a shell while loop does work.

Adding looping to "rosbag --clock" would allow it to publish the
/reset_time when needed.

rviz has explicit handling of backwards time jumps for this case. I generally do a bash loop, i.e.:
while true; do rosbag play --clock <bagfile; done