"If a generated password is ever compromised, you don’t need to memorize a whole new secret key and update all of your passwords. For that service only, just add an incrementing index to your secret key. For example, if your key was bananas, just use bananas2. If you can’t remember which iteration of your secret key you used for a particular service, simply try them all in order."
In particular, you don't have to use the same secret key for all websites. It's okay to slightly modify one if that password is compromised.