~ Take her to the potty at the times you know she usually goes, like when she wakes, before and after meals, before and after naps, before and after baths, and before bedtime. Keep her there, don't let her jump up, by closing the bathroom door, reading to her, whatever it takes to keep her entertained so she learns to actually sit a bit. Have her sit when you are going and explain the process (yes, she's learning but you're going over what you are doing will reinforce it.) Do it at the same times each day so she gets into the routine, right now it's still a game to her.
~ Give her a book or books she looks at only when she's on the potty to help her relax and sit for longer spells.
~ Run her to the potty when you see she's going to run to another room to go in her pants, once she does it in the potty it will help her start to make the connection of doing it in the potty.
~ Start teaching her NOT to use the floor, as she may think it's OK to do so outside your home (I read something about a 6 year old doing this awhile back here on Mamapedia.)
~ Do at least a week or so of bare bottoms, so she can get to the potty easier. I used cloth trainers as well, but the bare-bottomed time helped to get the basics down, the pulling up of undies came later.
~ Be consistent in your efforts to train her, or be content for it to take some time if you continue to let her lead you, at 18 months she's the optimum age to train, per what I have read and observed in the many toddlers I have trained. My guy was ready at 19 months but I went against my gut and waited per our pediatrician's advice, and he then resisted and fought me and didn't train until he was 27 months, and it was a rough several months that resulted in him holding his poop :-/
Just make it less of a game to her, and a way of life. Oh, and duck tape the diapers, ending the tape in the back so she can't get them off, covering with overalls/shortalls on backwards so she'll keep her diaper on. We had to do that around the time my guy was her age...they want the diaper off but not to use the potty so you have to outsmart them ; )