A nine rounder requires a good deal more stamina than a single weekender in some ways. The experience can be compared to playing two four hour games each day for five days. Weekenders are very intense; but a lot of long daily games can sap you by the last few rounds.
Whenever I prepare for a tournament I always do the following basics:
-Prepare Rook endings of all sorts. This I do by culling real life Rook endings from my own games, be they +-3 pawns, and play the positions out against Fritz (no mercy settings!), at realistic time controls. If you have an increment in said tournament, make it 10 mins +30. If not; make it a straight 15. If you can't beat Fritz when you're 2 pawns up, who can you beat?
-Prepare pawn endings! This is often overlooked. Many times I have seen people graded in excess of 145, who should know this stuff; allow me to exchange in to winning pawn endings. That said; you still have to win them! Play against Fritz, or if you have a bible on the subject, go through them with that.
-Look at my openings and prepare them properly. At your level (above me), in that sort of a tourn, it is essential that you know what you're going to get from your openings with best play; and that you are familiar with master level lines or continuations. I played in the British U150, U160 and PM Open. On a few occasions my knowledge was unsatisfactory, and I was left behind in time at the board in the early middlegame. Best way is to look through DVDs you have on said opening; but also, annotating your own best games is a fine way to find improvements. At the end of the opening, note the main positional features, and how the position might transform. You can just sit and do an analysis session, as if it were correspondence, leafing through moves with your engine ticking by on blunder alert, improving here and there. The other facet of opening and game understanding is of course book theory. If you play anything sharp (Sicilian Najdorf attack lines for White; anything super tactical), it is essential that you do some revision and go a few moves deeper into theory than you have before.
-Do tactics puzzles, at your own pace. I say this because I personally find sometimes that if I'm doing well (over 1850 on Chesstempo well) I can avoid over intensive study, which can cloud me positionally. You especially want to make sure to be seeing intermezzos, and odd sequences without having to stop and find them.
-Revise your biggest weaknesses. For me, last time this involved looking through Simple Chess/Reassess Your Chess, with the caveat that looking too much at such things on a base level can deeply interfere with your subconscious thought processes. I tend therefore to complete this process about 2-3 weeks before my tournament starts, so that I can re-fuse my own thought process back to the right level.
-De-stress mentally. I don't know what job you're in, but mine is rather intense, and my sleep pattern is always rather arcane! So I sit one time and remind myself that a bad night's sleep doesn't stop me playing good chess (a light breakfast and emphasis on tactical shots will see to that), but that I'm going to the tournament to enjoy myself, because I'm a good player, and it's a holiday. If you do al that, the rest will follow.
Hope that helps!