We will charge 1,000 yen to extend "all you can drink" by 30 minutes.
or
For a 30 minute-extension of "all you can drink", we will charge 1,000 yen. bu doğru görünüyor mu?

The first one is okay. If this is for a serious establishment it would probably be okay. For a casual place, like a bar or hangout, I would probably say. "1000 yen for 30 extra minutes of "all you can drink" " if this is on a sign. If it's verbal, I would say, "It will be 1000 yen for 30 extra minutes of all you can drink."

For Americans "all you can drink" really isn't what we would call it. We would say "refills" or "drink refills." You could say "1000 yen for thirty minutes of (drink) refills". I am not sure if this would be the case with British English. In verbal casual conversation I would definitely use refills. I have never heard of "all you can drink" even though we use "all you can eat" commonly for buffets... I never really paid attention before, but when thinking of it, nobody really says that.