I nearly did this 18 years ago. I still have the draft email I was about to send to my consultant to give me the bag back.
I never did, and took it upon myself to get better on my own. Much like others have found here, I used Metro and Cipro for only short 24hr bursts, or 48hrs, then immediately off. Eventually the gaps between requiring antibiotics got longer and longer and longer, over a LONG time, and once I went a full 12 months without needing a single tablet. I used to even take Codeine to slow things down, I tapered off that and take nothing at all any more.
It was a long, hard, slow road, with a lot of exercise, dietary changes, determination, ups and downs, and having a J-Pouch is always going to be a compromise.
I would think LONG and hard about this, it took me 4 years to get to a stage after my last operation where I was even close to being "well" in what terms a normal person might consider.
Also believe it or not, during the times when my pouch was really bad, McDonalds was one of the very few foods that did not irritate it! Go figure eh... absolute junk, but for some reason never gave me an issue when I was unwell.
I know you are 18 years in, which is a good go, maybe they can give you a temporary stoma again to let the pouch heal up?
If you ever want to talk PM me a message.
I am 43, and had my final surgery when I was ~23/24, so thats coming up for 18-20 years.