I don't use published adventures, but I've ran my group through levels 1 to 30, so I have some idea of how character capabilities change. My first advice would be to replace all monsters you find in that adventure, especially solos, with similar (reskinned if necessary) monsters of appropriate level, preferably from MM3 or MVs. Monster design is a part of the game that got much better with time. And monsters designed for high level will probably have suitably nastier abilities. At the very least, make sure to use the updated monster math from MM3 (official errata pdf; alternatively, a very useful cheat sheet). If you use adventure tools, don't trust their uplevelling method - damage tends to be off. Skill DCs have also been updated at some point - included in the linked errata.
At low epic, the party will likely have people who can teleport long distances and/or at-will, they could also be phasing, and will most likely be able to fly. Go through the encounters in the adventure and make sure they don't get absolutely wrecked by these movement modes. You could introduce terrain features that negate some of these abilities, like an astral turbulence zone into which no one can teleport, but this should be applied with extreme care so as not to ruin the fun players derive from their cool abilities.
A higher-level party would also have access to higher-level rituals, which they may or may not use depending on the group. It's very hard to give advice here, as rituals are pretty random in 4e, so just keep in mind which ones your players tend to use.
