I find all these post on feeding Nepenthes coffee very unscientific. You see, people say that they see an improvement in the growth, but I've yet to see a conclusiive post or paper where identical plants are grown in identical conditions, with one set being fed coffee, one being given non-urea fertilizer and one getting nothing - as a control. Now, I expect that the ones getting coffee will grow faster , as they will utilise the nitrogen but I strongly suspect that the ones given fertilizer would also grow faster than the control. So, what would be the benefit of giving them coffee rather than fertilizer? Fertilizers are formulated to provide a balanced feed, coffee is not. This is not to say the fertilizer is better for Nepenthes than coffee, or vice versa and eventually both might harm the plant but until someone performs a proper experiment, I remain unconvinced.
As an aside, I too feed my Cephalotus with urea free fertilizer, as per Av, but I would not consider feeding them coffee until I see a lot more evidence to its long term benefits over fertilizers.