Honestly, I have trouble replaying most games. This holds particular to RPGs as I largely no longer care about story. I bought FFT on PSN a few months ago and never got past the fourth battle, just because I had memorized it when I was 10 and pretty much never forgot it. There is the occasional game I replay, though:
Earthbound: Easily my favorite non-MMO RPG of all time, in terms of story, characters, and art style/music. FFT edged it out in pure gameplay, but I still vastly prefer this one. Always loved its contemporary (though now dated) Americanish setting instead of high fantasy or sci-fi, loved the humor, the general quirkiness, and the light-hearted mood. You know, that light-hearted mood that gets mutilated, crushed, and incinerated in the last 5% of the game to give your 8-year-old self some of the most profound nightmares of his childhood. I've replayed it a few times. Giygas still creeps me out.
Oddworld (the first two): Another of my childhood favorites, for much of the same reasons. Humor, characters, and nightmare fuel. Played through the first one on Steam about 6 months ago, got 96 of the Mudokons without a guide. Fuck the Xbox games.
No More Heroes: I don't know why I replayed this of all games. It has some serious flaws. And yet, it's mindless fun, and I like Travis simply for his sociopath...iness. It helps when you swing your arms around far more than you need to. Need to get my Wii back sometime to play the sequel.
Most of the other games I like, despite the facts that I greatly enjoyed them and they still hold a place in my heart, I just can't bring myself to enjoy as much as I used to. These include Gran Turismo/2/4 (skipped 3), FF7/8/9/X, Unreal Tournament/2k4 (3 was okay but got old fast), Half-Life Deathmatch and its various mods (except CS), Morrowind, DMC3, the list goes on.
But none of these compare to my undisputed #1 game of all time, City of Heroes. It has since been shredded into very tiny chunks of its previous self, but back before the Issue 13 PvP fiasco, I played this game no less than 5 hours a day, every day. I logged over 1500 hours into that game...on just my main character. I had 7 other max level characters with 100-600 hours each. In fact, if Issue 13 never happened, I wouldn't even be here or on SRK -- I'd still be PvPing in that game instead of playing fighters.