This is going to sound strange...but then again, look at the questions we get on this forum.
Deja vu is us, as a soul, re-visiting that same moment in our physical bodies again. Sounds strange I know. Why would we want to do that? There can be a variety of reasons depending on the person. It could be an important moment that we want to change, make a different choice, say something different, have a validation about something, or even enjoy the moment again - I've had a variety of each of these and I'm sure many people have too.
Yes, we can have a dream about something, see it precognitively, even plan it while asleep and then it comes to pass. But typically to me it has a different feeling to it and I'll remember that I had a dream/vision about something when it does actually happen. With deja vu I could tell you exactly what the conversation/actions are going to be with everyone involved - it is that crystal clear and a decidedly different experience - for me at least.