How to sleep well after a major code refactoring

We all change our mind and realise that our code needs a major refactoring in order to meet new ideas. In the Aeternity blockchain project, this has happened several times. A blockchain is very sensitive to changes because blockchains elementary are based upon hashes of terms that should match with earlier hashes. A change that causes a hash to differ could mean that people can no longer access their assets on the blockchain.