I don't think you can lunge a horse to blow off steam and teach it respect at the same time. I also don't think that it is an attractive thing when people brag about being able to sit down, read, or pretty much ignore their horse while it is lungeing around them. Lungeing can definitely be a platform to teach respect, among other things, but it should involve both parties being actively engaged and focused. You are going to have to nip the problem in the bud as soon as you see or feel her intention to charge you, and the only way to do so is to be competely focused on her movements so you can correct them before they have already begun to occur. Let's say you decide to lunge her using a line, and let's say you decide to do it in an enclosed area. There should be tension in your line at all times, not excessive tension, but most certainly a feel for her head. No loops, whirls or what have you. Arms, just like when riding, should be controlled, close to the hips. You should be able to feed and collect rein with your whip hand as needed. Your positioning should remain behind the driving line (at least where the girth attaches) and it should not vary much, because though it may not seem like it, the horse will notice your positioning. Now, we know your horse does not need much gas. So although I still recommend you carry a whip, I advise it be pointed at the shoulder, mostly. This will encourage her to stay out on the circle. When you have a horse that has alot of go, more often then not, they seem markedly straight thoughout the body. When you look at a TB while racing, you can notice they have a tendency to "lock" up, in this position. So getting a slight bend in her without allowing her to turn in would be ideal. A horse running like this around the ring will most certainly give you signs he/she intends on turning in. You just have to have enough follow through to notice this right away and flick the whip at her shoulder to keep her out. If she turns in takes steps towards you, this is blatantly disrespectful of your space. Own your space but don't start any battles you don't intend on winning. If you were just another horse, you have to ask yourself, who would move first?