Most of your energy will always naturally go to the top of the plant where it has the best chance of benefitting the plant. The best way to get better growth on the lower part of the plant is to bring it closer to the top. The easiest way to do that is to bend to top of the plant over as low as you can safely get it without breaking the stem. I would normally top it, but considering the health of that plant I wouldnt do it in this situation. Just gently bend the top and tie it down. . This will get better light to the lower nodes and it will trigger the plant to send more energy to them