I think with bipolar, I am schizo-affective which is similar and mental illness takes its toll on the physical body. Daytime sleepiness can be part of the need to take a nap to stay stable.

I would suggest to let her sleep in the daytime if It is not interfering with anything. Perhaps a scheduled 2 hour nap would resole the daytime sleepiness by actually letter her nap. Her body knows what it needs.

I would not mess with the klonopin, without contacting the pdoc and perhaps after time her need for a daytime nap will decrease. It is a good thing that a bipolar get their sleep, as the opposite is more devastating, not sleeping at all can lead to psychosis.

Just my personal opinion,
kk101