As others have said, lower ab fat is the "last to go"- so you'll need to keep losing fat on a systemic basis.
Everyone's bodies are different, so you'll need to experiment. Here are some methods I've found anecdotally effective and logically compelling. IMO, choose between 1 and 2, and incorporate 3-5 as much as you can. 6 is just an FYI.
These strategies are obviously within the context of a high quality paleo diet- I feel that processed foods promote body fat storage independent of their caloric value via their inflammatory (see Jaminet) and food reward (see Guyenet) effects.
Personally, I've found 2-4 to be most effective if already <15% BF, 1 and 3-4 is best if you're >15%*.
*Lifting: Also note, the points about cortisol and overtraining are valid. I've found 2-3 lifting sessions to be optimal for fat loss. 4+ precludes sufficient recovery.
1. Quilt's "Big Ass Breakfast" - 50+ protein for breakfast kills the appetite and amino acids rarely become fat. Tim Ferriss has also shown anecdotal support for this. Don't get too caught up in Quilt's theories on circadian rhythm, but feel free to geek out on it if you want.
2.Martin Berkhan's lean gains protocol. I've found fasting to be effective for fat loss only in the context of fasted lifting and its effects on MTor signalling. Fasting without lifting only seems to slow down my metabolism (less cal in, lass cal out, zero delta).
3.Maximizing NEAT (non exercise activity thermogenesis) Stand and walk as much as possible during the day. Travis Culp has some good answers on this, and Quilt mentioned it in his most recent post. Seems to work even better fasted (search Culp's answers for why).
4. Carb/Fat cycling. Advocated by Jay Robb of protein powder fame (he's not paleo but the concept still holds). Berkhan also. I go mostly eggs, coconut and salmon on my fat days (dairy and nuts seem to be fat loss headwinds as discussed here often). Carb days I go sweet potato, eggs, steak/chicken, sometimes rice/plantains/white potato.
5.Coffee/Tea. Not a huge fan myself, but obviously a popular adjunct.
6.Water retention. People confuse fat with water quite often. Recognize that as carbs/sodium go up, water will be retained in concert. This isn't bad, but can dishearten if not recognized as such.