Unfortunately, Riot does not have any current plans to overturn permanent suspensions issued for violations of the terms of use/code of conduct. Only those that were issued in error are overturned. It is possible that this might change in the future, but currently, the loss of skins/rank/champions/level 30 is basically the final punishment for players who do not respond to any previous punishments. It is meant to be permanent.
If Riot overturned permabans for every player who said they had reformed, almost every player who was permabanned would say they were reformed. If I'm remembering correctly, in the past Riot has actually tried a program where banned players were given a chance to prove they had reformed, that failed with the vast majority of them showing that they had not in fact changed.
I am sorry that at this time, we don't have a more positive reply for your situation. Perhaps in the future it might change. If you really enjoy playing league, it might be worthwhile to play on a new account. It is much faster to level accounts now, and with the loot system, you will have access to skins without having to purchase RP, if you do not want to spend money on a new account. Best of luck in the future, whatever you decide.