Archive all the other channels that are not the main and go back to the main first few. Change the theming as in if you are using emojis in channel name, swap to another batch.

Bring something different. Old chat is boring, the new users can't relate, old users shiver at their cringe. Don't delete, archive, make a category called Museum and shove them there. You've got to offer something, a Minecraft server, free money and please get rid of any of those stupid "level up bots".