If you defined the connections as Resources (FTP, SFTP, FTPS, etc) then pointed to those resources, all you would have to do is to modify the resource and it would switch from Test FTP to Prod FTP (ie, change the IP, userID/Password, etc). Once you test, then save, it would affect all Projects that use that Resource.
Another option is to create a Folder Variable indicating whether job is to be run as TEST or PROD. Then, inside your project, check the Variable. If equal to PROD, use PROD FTP Resource, otherwise, use TEST FTP Resource.
There are several ways to accommodate this.