What I do, to edit Add-Ons ingame, I edit it, then I save it to the file (which pops up when i close it) and then ingame, I would type something like this: setmodpaths(getmodpaths());exec("add-ons/YOUR ADDON HERE/server.cs");
in the chat (Since I have eval) and then to make sure that it worked, I do TransmitDatablocks();
Note: If you do edit an addon ingame with players on your server, it may force them to disconnect due to an invalid Packet. They can just reconnect, but I'm telling you since it's happened to me before.