T.F.
2 ideas...
1) Taking away privilages instead of time out. Whenever possible, try to connect the consequence with the incident. If you can't, take away TV, computer, playing outside with friends, certain toys,whatever she does in her spare time.
2) More effectively, though, may be what you said you've done in the past, which is just talking with her. My daughter went through a lying spurt and my husband and I made a BIG deal about how now we can't trust ANYTHING she says. We had to illustrate how telling lies makes it difficult for people to trust you. No one can ever tell if you are telling the truth or telling a lie, so always be truthful and you'll be trusted. Once she started telling lies, we treated everything she said as if we couldn't tell if she was lying or not. Example, we'd ask if she brushed her teeth. She said yes. We said we couldn't trust her anymore-- how could we tell if she was lying or not? And we made her go and brush them again. If you do this for a few days, she will be miserable and get the point. Let her know that once you become tagged as a lier, you have to build back the trust. After a few days, we told our daughter that we believed her and trusted in her and would like to give her a clean slate, and we hoped that she would not back slide and tell another lie because then she would shatter our trust and we'd be back to square one
Also, kids don't hear the stories anymore that we heard as kids, so she may not know about the boy who cried wolf-- tell her that story