Hi, welcome to the forum, the modalities to improve narcolepsy symptoms are not much but available drugs can help your symptoms. If you are on high dose of modafinil then next you can be put on other drugs which can be helpful in this condition.
Having regular nap for about 20 min during day will help to prevent sleep attacks. Drugs apart from Modafinil, which can be useful are Methylphenidate, Gamma hydroxybutyrate and Amphetamines against prescription can help to increase the alertness during the day and they are esp. useful in excessive daytime sleepiness or increased sleep attack. For now you can continue the treatment, later if needed can shift to other class of drugs. I suggest you to consult physician for further evaluation. Take care and regards.
I do relate to your frustration. I was just diagnosed with N last month although I've been working with a dr who has had me on various stimulants for a couple yrs now. After watching my mom struggle with N practically all my life, I'm terrified I will end up between a rock and a hard place. But I also know (and want to remind you) that the medical field's understanding of sleep disorders is maturing everyday so even though it may seem like you are out of options, there may well be more tomorrow. I also want to suggest a couple meds in the meantime. Although I personally hate taking meds, I have had to accept that sometimes they are necessary. To supplement the modofanil, you might want to discuss adding a shorter acting stimulant like aderall (not XR) or maybe Xyrem for deeper sleep at night?