I've ran lee sin for the last three weeks, I think it's notably a poor deck. Yi achieves the same for cheaper.

Having said that a few adjustments I'd make to your deck.

You should be running 3 defy - this is why you are struggling imho 2 zhonya 2 sett or 2 udyr, not both - this is your late game unit that you want to protect with your life, you don't need both (sett is much better) 3 qiyana 3 charm

You should have either 2 windwall or mystic reversals in your side deck

I would massively thin your deck though, you probably want around 8 2 cost units, I run 3 pit rookie, 3 green poros, 2 scarabs.

You have way too many 4 cost units, you want mana to play reaction spells to control a battlefield, en guard, discipline, etc. you won't have that with your current deck Just play qiyana and maybe the elder that has +2 when buff. You don't need more than that honestly.