For my setup, it looks like I have to restart to get the name to be recognized. The difference might be that I use a tnsnames.ora file and in the same directory I have a foonames.ora file that I reference in the tnsnames.ora file using:
IFILE = C:/path/to/network/admin/foonames.ora
foonames.ora gets changed daily as a scheduled task grabs new tnsnames for new VM's as they are created, and then puts the new names into that file. Any way I can get that to load without needing to restart pl/sql?