Superman's costume is made from the blanket which he was wrapped in when he first landed on Earth. The alien properties of the blanket make the costume nearly indestructible. But, I think its stock is limited & it doesn't have replication/ regeneration properties etc. (Correct me if I am wrong).
In an episode of Justice League, Toyman sent Superman to the future, when the Sun was red. Unfortunately, it looks like the costume also needs yellow Sun for indestructibility. Look what happened:
How did he come back in action with an indestructible costume?
In Justice League Unlimited, once the government's Cadmus project created a monster with Superman's DNA who was powerful enough to tear Superman's costume apart:
But again, it was not a big problem for Superman. I don't know from where Superman got a shiny new costume in the same episode.
Does Superman have access to Kryptonian cloth reservoirs? Are there other things I am missing?
What's the secret behind this?