ePirat is right, you have to reconnect. However if you are concerned about ‘losing’ some tweets during the changeover, there is a short grace period where you can have two connections with the same credentials running.
So you could create a new connection with the new filter terms (add and/or remove as required), and once that has started (X seconds later), shut down the old one. Just make sure you don’t leave two running with the same credentials or you will get them being disconnected, and potentially get any new connections blocked after a short while, and ultimately black listed if it the behaviour persists.
Cheers,
JB.