hope she feels better soon.
You could try putting her down a bit later on a regular day, but don't push too much or she'll go hyper.
I guess the WI/WO I mean is just making her get back into bed and constantly repeating that it's nap time not play time. Do you prepare her before nap time with a lot of 'it's nap time soon, which means we don't play, we have to rest and sleep.....'?
You could try offering a treat if she naps? Hardly ideal I know but just till she gets the hang of things maybe.
Does a good telling off work? Once DS got out of his bed and followed me out the room, I was on the brink of laughing but did a big act of being cross and said he should never get out again bla bla, and he hasn't-whether it's because of that I can't say of course, but it might be worth a try.
All the best!