If you lose the password the signature is lost forever.
Do you mean password on your signing credential (certificate) file, .pfx or .p12? The password on these files is not resettable, it is set by whoever created your credential (usually a Certificate Authority or yourself if you created a self-signed certificate). You can use the same signing credential many times as long as you remember the password. If you forget the password, then that's it, you lost access to your credential.