^ They didn't print enough of the interview to understand the specifics. My guess is when he refers to the eight percent more, I think he's talking about the DVD not the theatrical release. (which he's saying is original... original as in home video original.) On the first part and the selective upgrading of 2,000 shots, this I think refers to how for the BD they selectively recropped (or returned to the theatrical cropping) because they were now dealing with the eight percent more frame. The 'cleaner, sharper, purer' could allude to the overall filters they apply to unify the shots... From everything else i've read so far, I don't get the sense that they at any time went back in and upgrade digital effects, for the BD/3D of TPM.
Let's hope Cinefex does a story, as that might delve into this at an appropriate level, to understand what they've done.
*EDIT*
Reading more of the article, when they talk about the 3D creation:
The process is, one 'eye' is the movie as you've already seen it and we're creating a synthetic left eye or right eye. You shift everything over, so if you imagine a stereo pair, the other eye is shifted over a little bit horizontally. How does the image change when you move over horizontally? Everything in the image shifts a little bit horizontally, proportional to its depth. So if you take depth information and use that to kind of shift everything over a little big, you've kind of simulating what a view from a second eye looks like. For all the objects that have depth discontinuities on them [something that's in the foreground over something that's in the background], now that everything has shifted over a little bit, you can see around it to a part of the image that wasn't there, so you have to reconstruct that part of the background that wasn't there. That's a process called in-fill and it's the most labor-intensive part of the whole thing.
*EDIT 2*
So did you have to re-animate any of that stuff?
No, mainly because it's old enough now that we use different compositing systems and shot directory back-ups. We keep them for a certain amount of time but after a decade elapses, nobody really bothers keeping hardware to read that stuff or old systems that can run the software that was used back then.