Do cables need to be re-broken in?

Electrons become slow and lazy after just sitting around for a while.

Of course. Only its minutes not months, and movement matters more so than time. In other words your system warms up every night, and all the wire not having signal running through it is a part of that warm up. That's with nothing being moved around. Moving a cable around, all the bending and flexing, it will be a few to several minutes settling in after that. Try it and see.

When the music sounds like it’s slowing down I just rub some Geritol into the cables nice and gentle like. Makes an electron feel like gettin up and going.

DBS is 24/7/365 Geritol for the Dielectric 72 volts for battery, more if device powered, 128 V on my power amps

I just ordered a loom of Triode Wire Labs and the owner Pete G. does a "preliminary" break in on a cable cooker before shipping.  He advised that shipping, uncoiling etc. creates a need for break in at the user end. He also says the "down" time between playing is important for the dielectric to season.

Reverse the polarity and it will reverse the reversal of not being used. 

People with lousy (nonexistent) listening skills love to crack jokes. The differences some of these things make are beyond easy to hear. One time I came home to a new IC and with little time between shifts raced to hook it up right out of the box. It was a used cable, should have been broken in, sounded absolutely horrible. Not imperfect, not disappointing, not bad. Horrible. Awful. Bad enough I lost sleep that night wondering what might have gone wrong. 

The next day at work it dawned on me, I didn't recall checking direction. That night first thing sure enough it was backwards. Switched around and warmed up it still needed a few hours to settle in but now it sounded really good.

These things do happen. They do make a difference. Just not a difference everyone is able to hear. That much at least is clear.

Does your chewing gum lose its flavor on the bedpost overnight?

Do cables need to be re-broken in?
Yes!

Bob Crump of TG Audio broke in all cables and power cords for 30 days on M.O.B.I.E. prior to shipping. The presumption is that cables or power cords NEVER break in 100% just playing music through them, not even in ten years. Maybe not even 80%.  Please, no angry PMs.

I know my house wiring hasn't broken in it takes 10 seconds to long to cook my oatmeal. 

Hi,
no, only let gravity do the work. A cable must sit and take a form.

It takes 381/2 hours for re break in.

Burn-in aside, mechanical stress with new or used coiled-up cables was a factor with most of my Cardas interconnects, and a few others tested over decades. Just letting them sit plugged in and relaxed for 10-14 days, not moving them and letting them rest did result in different results with sound too. More noticeable in transparent systems primarily. Makes little to no difference in less transparent systems or low grade metallurgy and no dielectrics used in cheap cables - still sounds grainy regardless of time, YEMV. 

According to George Gardas:
http://www.cardas.com/insights_break_in.php