I started using Super Thrive this past year for root growth and I think it does help specifically with that. I know others use KLN or other products with good results too. I had a pseudobulb on a cattleya that broke off when I was repotting, a single bulb, and I thought it would die but it is hanging under a bench putting out a new growth and very happy. I like to soak/drench a plant that is without roots with 1 or 2 drops of Super Thrive in a gallon of water. I don't use it as a fertilizer but just to promote root growth or for very stressed plants.
I am wondering if your plant could use a bit more light? Umm... is that a root under the leaf peaking out?