Is Redensity 2 the right product? (Photo)

After a terrible experience with fillers 6.5 years ago, which left me with a duck look, my lips are finally back to shape. I’d like to plump them a little - super natural effect, preserving my shape and avoiding any filler-like look. My doctor recommended 0.4ml of Redensity 2. is this the right product for lips? Am I running any risk of activating the old filler which is still present at the very top of my lip and getting the duck look? In the past I had 0.5ml x3 in 6-12 month intervals.