I like Wendi's answer quite a bit, but I'd like to add that you can even make your comments shorter if the context makes it clear that you are talking about the presentation:
Bill, I'll see you tomorrow.
Oh no you won't! I'll be presenting at the conference.
Oh, I forgot about that. Best of luck!
Here, there's no need to say "with your presentation," because it's fairly apparent that's what you're talking about.
In addition to "best of luck," there are a host of other informal phrases that could be used, such as:
Knock 'em dead!
Break a leg.
I hope you wow them.
I hope it goes well.
Knock 'em dead is an expression that means, "I hope you're presentation goes so well, that you absolutely stun them." "Dead" in this sense does not mean "absent from life;" it's more referring to "dead quiet" or "dead calm," and the implication is that the audience is "dead" because they are thoroughly impressed. Cambridge calls the idiom "informal," and gives this definition:
used to tell someone to perform or play as well as they can
Break a leg is usually used in theater, where's it's considered bad luck to wish someone good luck, so you wish them good luck by saying, "Break a leg!" Though it's usually given to an actor before a performance, I've heard it borrowed for speakers giving a presentation. The ESL Cafe website even gives this example:
"I understand you have a job interview tomorrow. Break a leg!"
In I hope you wow them, NOAD lists one definition of wow as a verb, meaning to "impress and excite (someone) greatly." NOAD also lists this example usage: they wowed audiences on their recent British tour. Indeed, when wow is used as a verb, it's usually used in conjunction with an audience; you can find several examples here, including this one:
The show started off with a bang as Mike Smith wowed the audience during his opening keynote session.
In I hope it goes well, go is a very flexible word; Collins lists over 3 dozen verbal definitions. Coincidentally, Definition #14 refers a lecture:
14. to follow a course as specified; fare ⇒ "the lecture went badly"
That said, any number of examples could have been used instead; in the saying "I hope it goes well," the "it" could refer to any number of things: a lecture, a doctor's appointment, a hiking trip, a football game, a commute home. "Went well" simply means there were no glitches, no snags, no disappointments, no technical difficulties, no injuries, and no bad news. In the context of a lecture, "went well" would mean the presentation was well-received, the presenter felt comfortable, and the talk went smoothly.