Is it possible to restart the unity panel without restarting compiz?
Solution 1:
To restart the unity-panel-service, just kill it:
killall unity-panel-service
If for whatever reason it's not running at all, you can start it via
/usr/lib/unity/unity-panel-service
Solution 2:
To do the same on Unity2d type
killall unity-2d-panel
or, if just the application launcher on the left fails, type
killall unity-2d-launcher