Yes, of course "omnes".
I have a doubt about line 3, because "anima mea" seems to be the subject (nominative) and its verb is clearly "magnificat". So I suggest to put "laudate" between commas, because it seems a sort of incidental clause, like a second voice.
--> "Et anima mea, laudate, magnificat in saecula".
A comma should be added at l.2, too.
--> "laudate, magnificat in saecula"
The problem comes from the fact that this text is a mix of two religious canticles: "Laudate omnes gentes" and "Magnificat anima mea".