Let's look at all the dialogue he has said in the series:
First of all, from the end of 1.0, he knows about Shinji while he was already on the moon.
The third again, huh? You never change, do you?
He did say the word "again" here, but it could mean "also" too.
But if you know that something doesn't change, you know how it was like before.
Later, he also refers to Shinji using the title "-kun" and the pronoun "kimi", both of which imply familiarity. Apparently, it's rude to use the latter with strangers. Whether this is saying something or just for effect, I like it.
I'm pleased to meet you... Father.
Despite wild theories to the contrary, he's probably just calling Gendou that because he's Shinji's father. Again, he is implying familiarity, even though that's quite contradictory with "I'm pleased to meet you." Either way, he knows this, although who informed him is still unknown.
Finally, here's the greatest extent of Kaworu's dialogue so far!
Come now, the promised time has come, Ikari Shinji-kun.
So he was informed of some "time." (Or maybe he just knew by himself...) But by who? And what exactly is it?
If he was working with SEELE as implied on being on their base in the moon scene, this would be going against their wishes. Or maybe they just want Instrumentality on better terms...
This time, I'll be sure to bring you happiness.
I think this is the most key piece of dialogue he has.
Even though I don't necessarily believe in the sequel theory, this says that if there's a "this time", there's a "that time" too. What could it be?
Also, it says that before in "that time", Kaworu did not bring Shinji happiness. Is this a implication that he knew what happened in Ep 24?
So, even though he has had so few lines, Kaworu has revealed quite a lot. What do you guys make of what he knows? Presumably, he will serve about the same function as in Ep 24, but do you guys think he will reveal more information on things this time?