A workaround in Cinnamon is to change is which monitor is the first/secondary, then the panel will follow.
I I learned today that gnomecinnamon-control-center's tool for screen settings allows you to do this. It shows the two monitors and a black bar at the top of one of them -- that bar symbolizes "first" (I guess it represents a panel at the top of the monitor). If you click on
NOTE: You can also access this barvia (as opposed to the monitor center) you can drag the bar to the other monitor, without changing the geometric arrangement of the monitors.cinnamon-settings too!
In Cinnamon v2.x


(We are not the only ones struggling to find this setting: https://bugzilla.gnome.org/show_bug.cgi?id=636216 )