I didn't get the technique upgrade in the Derelict Building on Hunter and Hunted on my first run through. The target is 6,000 and I only got 5,000 which is what you get for getting to the goal. I replayed the level from there and got 6,250 (I upped the difficulty to get a higher multiplier) but the technique upgrade didn't unlock.
Do I have to do it on the same difficulty I did it the first time? If so, how can I get an extra 1,000 points on that section?