Child that keeps lying

I need some real advice on how to handle this issue before you read this if your comment is to say she is a child get over it then don’t even comment cause that literally would be useless and no help.

So my 7 year old soon to be 8 in about two months had been lying and doing more and more thing she isn’t supposed to it started about a year ago with little white lies not really a crazy big deal then she got a good talking to and grounded. Then it started to get worse she is lying about what she does it school she lies and says she does something when she doesn’t it’s not small things that she is lying about. Once big rule we have is her not touching her sister because she never washes her hands or is always wiping her face and we don’t want her to get sick she will try and sneak and touch her sisters face or will put her face in her sisters face she has even acted like she wanted to hit her sister before these are only a few things

I have tried to talk to her I have even tried to have a clean slate and let her know that when she is good and doesn’t lie she can watch tv and get rewards. I even tried spending one on one time just us this doesn’t seem to work at all. The latest lie was her playing outside and asking a kid to pull down there pants behind a garage she lied and tried to blame it on the other kid until she relished someone else was there to witness it.(I was at work at the time she use to stay at the neighbors to play).

She seems to not care about getting in trouble and it’s to the point now we think she will try something with her brother and sister does anyone have any advice that can help cause I honestly don’t know what to do. I have even tried to have my mom talk to her since she is a big part of her life as well but she just says ok and keeps doing things over and over wrong these aren’t the little things that kids do it’s big things and it’s not ok.