You shouldn't have to take the station off the air (or get knocked off the air) with a little proper planning.
Don't Try This At Home or Without proper Adult Supervision.
Pretty simple actually...
Your video,audio and data links all (presumably) have active back-up paths and circuits, that are used for maintenance or emergencies..
They are extra channels or spare "pipelines".
On the big day, all you do is switch to the back-up circuits while you shut down the "main feeds" and establish and test the new signals.
Once you are happy with the new signals...you just switch back from the back-up line to the main lines.
...and since you did a secret "test of the test" a few hours or days before...you are certain all will be fine once it's all "official".
Practice Safe Engineering for a Green Planet.