I am hoping there is a single command I can issue that will update the tor bridges, so that I can add that command to a cron
What do you mean by update Tor Bridges? Replace all existing bridges with new ones? Even if you wanted to use a new Bridge say, around the time Tor entry guards would rotate ( primary lifetime of 120 days). I think it would be OK to keep them for a while since there are default multiple bridges included with Whonix.
Not sure if there is a single command to rotate just bridges. Even to remove Tor state (or bridges), then running Whonixsetup (or add new bridges) requires interaction with the konsole.
ok, Thank you, I will figure something out =]
Free Support for Whonix ™ applies because of Frequently Asked Questions - Whonix ™ FAQ.
Because of Whonix ™ - Anonymous Operating System any solution that would work for Debian will also work for Whonix. Just replace the config file name which as of Whonix 14 is
/usr/local/etc/torrc.d/50_user.conf. (Can be found here :Tor - Whonix)
Changing bridges by cron… I don’t think I saw any bridge cycling advice from Tor Project.
Good read on some background:
Which comes with some interesting quotes:
The following is a reminder about bridge versus non-bridge anonymity: 
Bridges are less reliable and tend to have lower performance than other entry points. If you live in a uncensored area, they are not necessarily more secure than entry guards.
Hey Patrick, Thank you for the links, I will review them now =]