I think all 14 year old girls lie.

My was barely human for almost 3 years... 13 to 15 and change.

Now she is a delight. But she had to do those things that she did to get where she is now

perhaps rewarding the positive will also have a good effect, sure there should be some accountability for the wrong doing, but when there is a good act committed, like telling the truth shouldnt that be acknowledged as well?

Sometimes bad attention is better than no attention.

just my opinion

I took away computer access, cell phone, mall rides..etc. Nothing worked but time

She might be going through something that happened in her past.

She could be testing her boundaries with you. All kids do that. That is where you CANNOT let her manipulate you.

Have you ever noticed if this is part of her normal personality?
There are people that constantly lie that have a personality disorder. This is the extreme. They say they have dated a movie star, etc. If you climbed a mountain, they did to.

If taking away privileges doesn't work, counseling (for her or both of you together) might help.