のじゃぞ shows that それまで、明日もここにおる is information the speaker wants to emphasize. (This の is for explanation.) If the subject of おる is the addressee, the relation between "I'll explain the circumstances tomorrow" and "you should stay here until that, also tomorrow" is reasonable to emphasize. Or, when the caution follows it, as in my examples "you should be careful against him" and "you should prepare a bed for me", "he'll be here also tomorrow" and "I'll stay here also tomorrow" are reasonable information to emphasize, therefore "he" and the speaker can be the subject of おる, respectively.
If のじゃぞ isn't there, the subject of おる is the speaker. In this case, it connotes "if you want to say something to me, you can visit me", and "I'll stay here also tomorrow" is not information the speaker has to emphasize.