Don't cast Jake Lloyd, remove all of Jar-Jar Binks' jokes (keep him around, just quiet outside the necessary Gungan scenes) and the Midi-chlorians scene and Star Wars Episode I: The Phantom Menace will pretty much shoot up in the minds of every person who ever watched it.
I can't really clean up Episode II, which definitely my least favorite of the films, and as long as Ep. 1 is saved, I think Ep. 3 is saved by lack of association. I've always felt Ep. 3 was a mostly beautiful film that just gets lumped in with it's two inferior predecessors.
But overall? I'd say butterfly away all the extra anticipation and buildup. Don't let fans have such high expectations in the first place. Make the movie more of a surprise to people when it comes out, and I think they'd give it a lot more credit without the hype.
I'm relatively a kid, and I find Ep. 1 and Ep. 3 solid and enjoyable films - definitely inferior to their predecessors - and I chalk that up to the lack of hype for me for Ep. 1, and the fact I hadn't seen the original movies as such a younger person in comparison. To a certain degree, Ep. 1 was as much a part of my childhood as the OT.