C.B.
My advice is to be patient with your daughter. A new baby is a lot of adjustment for a 2 1/2 year old to handle, and sounds like she's just reacting to the stress of it all in her own way. Sounds like maybe she's seeking extra love and attention from mommy and daddy since the new baby probably (understandably) takes up a lot of your time.
My daughter was the same age as yours when my baby boy came. She went through the exact same thing with sleep problems including naps and bedtime. It was so tough for a while as I was so sleep deprived anyway with being up all night with the baby, and my husband went back to work a week after the baby was born. But after a month or two, things fell back into a routine, I was more confident with handling 2, and big sister started to adjust to having a baby brother. Then all of a sudden her sleep improved. I found that on the days she acted up either at bedtime or naptime, that she was really just seeking extra attention from me. Once I gave her what she needed, maybe some alone time with me or extra hugs and cuddles, she always settled right down.
I know it's so tough, when you need all the sleep you can possibly get while taking care of both kids, but hang in there. It will get better!