15lbs is about 6.8kg so 8 weeks to lose it all is probably do-able. I would calorie restrict, get in the daily cardio (not too much) but the cardio seems to be important for bodybuilders when they are cutting. Not that you are a body builder or even say a fitness model but they know how to get the fat off fast to be competition ready. Keep the protein high, do weights or Crossfit. About 100g of carb and lower fat.
Did you lose 18lbs in 2 months? How did you do that - it was paleo but what sort of macros. Maybe do the same thing?