You can also split it into several items and apply different FX to different items.
Either way, things get a little more complex when you're talking about "echo" whether you mean delay or reverb or both because these things have "tails" that go on after the source stops playing. If you just bypass the effect, then the "tail" will just end rather than naturally fading out. That might not be a problem. Maybe there's room on the track for the effect to tail out before the vocal comes back in, or maybe the abrubt cut off will be masked by other things in the mix, or maybe it's what you're looking for.
If it is a problem, then you need to put the effect on another track and automate the send from your vocal track. You could mess around with routing on one track to make it work without adding a track also, but it's probably more work than it's worth.