I've not bothered with this plant because I know I have insufficient light. But I can offer some guidance on your question.
Aquatic plants require 17 nutrients. Photosynthesis is driven by light which must be sufficient intensity to meet the need of the plant species (there are fast growing and slow growing, with varying light requirements). Substrate plants usually need more light because it has to penetrate the depth. The 17 nutrients have to be in balance with the light intensity.
Those with experience with Creeping Jenny can offer more, but will want to know your lighting data and tank size.
I will just say that a comprehensive fertilizer is necessary rather than adding a few individual nutrients, unless it is certain that these are specifically lacking and the others are present.
I do not recommend Excel, as it is a glutaraldehyde compound and highly toxic. I just posted on this in another current thread so you can see that for more.
Byron.