I see no reason why we'd change the way we "spend" powers just for Full-Discipline powers.
So I'm fairly sure that if you don't use the Movement technique of a Full-Discipline Encounter power during the round you tap it, then you lose it, 'cause the power is now gone until replenished.
So they provide great options for the rounds where you use that technique, but that's it.
I can imagine certain situations where you need a special maneuver, so you tap the movement ability of a Full-Discipline Power, but don't want to use that attack for that situation. In that case, you'd just use a basic melee attack or a non Full-Discipline standard action. But either way, your Full-Discipline power is still spent, so you can't use the attack option in a future round.