Having just done this, and helped 4 others with similar issues on the same beer, there are some things I've learned.
First, on a beer that you add sugar to, wait until the primary fermentation slows a bit, then add the sugar (about day 3). If you add the sugar at the beginning, the yeast eat the easy stuff (CRACK) and don't want to work at those hard enzymes in wort.
Second, while this doesn't help in this situation, if you can re-aerate at about the 12 hour mark, do so. The timing on this is critical. You want the yeast to use up the existing O2, but before you would cause oxidation.
Third, as MalFet mentioned, use proper temp control. I wanted a full range of flavors, but wanted to focus on the spicy/fruity esters. Using
White Labs Belgian Chart, I focused my temps on the 65-75 range for the first full week or so, then when things slowed down, raised it up to 78 for a couple of days.
My 1.076 dried out to 1.011, and I think it has probably lost a point or so in the secondary based on the carb and a refractometer reading. This took a little over 2 weeks in primary, and 3 weeks in secondary.
I would do some research, but you may be able to use a very clean yeast (S-05) and add to that, since you've likely created the ester profile for the belgian.
Good luck, and I hope this helps someone.