Bro, adding sugar or molasses to your soil doesnt increase the brix of your plant. High brix growers cultivate a lively microherd to digest soil minerals. While sugars will feed soil biology it would only be useful up to a point. The goal is to cultivate a diverse microherd that are cycling nutrients present in the media.
Also checking refractometer values is better than nothing but its utility is limited. There are lots of factors influencing those readings e.g.time of day, position on plant, extraction method, last feed, moisture level, operator contamination etc
If achieving high brix results were as simple as adding molasses there wouldn't be a soil consulting industry.