The SSL/SSH/FTP is a strange mix. I assume that by SSL you mean SSH. But I'm not sure if you really mean FTP, or SFTP.
It's also not clear what "password prompt" did you use to change the password.
Some screenshots and/or logs would help.
I have been trying to figure out how to automatically change a password when a FTP site prompt you that your password has expired. I just review my log from and SSL site that said my password expired. It said in the log that I can change it by typing oldpassword/newpassword. I logged in manually and at the password prompt I entered oldpassword/newpassword and the site updated the password and I was in. I logged right out and back in with just the new password and I was good with the new password. Does anyone know if this can be done with and SSH site and in you can do this with WinSCP in vb.net?