I don't know the answer if they have come to the end of their lives, but I suppose one thing we can do (and you may well be doing it, so I can add a lesson on sucking eggs if that would help!) is to wear our clothes for as long as we can rather than have a new outfit every five minutes. If they don't fit any more, or you really can't stand them any longer, someone else can get the good of them if you put them to a charity shop.
Another thing would be to buy natural materials where possible. Wool and cotton would compost. Organic cotton still uses a lot of water, but not the pesticides that non-organic cotton uses (so presumably pleasanter for the farmers to produce).
I have to admit to having learned quite recently that viscose is not another plastic but is made from plant material 