How to continue a Docker container which has exited

docker start -a -i `docker ps -q -l`

Explanation:

docker start start a container (requires name or ID)
-a attach to container
-i interactive mode
docker ps List containers
-q list only container IDs
-l list only last created container

You can restart an existing container after it exited and your changes are still there.

docker start  `docker ps -q -l` # restart it in the background
docker attach `docker ps -q -l` # reattach the terminal & stdin