[spidey]

It's pretty normal for a dog to start checking the boundaries in that 1-2 year age range, not only are they maturing mentally and physically, but the hormones start percolating as well as they start hitting puberty (is she spayed?). I'd just keep up with the training, don't come down on her like a ton of bricks, but do make it clear what the rules are. There's also no harm and quite a few benefits to taking a couple of steps backwards and going over the areas you've already gone over (there's always room for improvement, even in the very basic skills, and I feel it's a better move to go back and reinforce things the dog's already been taught than to try and work on new or more challenging things when the dog's in a silly phase). Off-leash heeling can be pretty hard work, especially for a youngster.

I've been experiencing this on and off with my pup recently (he's 15 months), one week he's a lovely boy with reasonably good obedience for his age, the next he's completely silly and doesn't remember what "sit" means. I just stay consistent, and when he's having a particularly silly time, we go back a few steps and refresh our memories of the basics. Patience is a virtue, especially with young dogs! :)