How long ago did she cut it?What did she cut it on?
How deep is the wound?
It definately sounds to me like she needs some sutures.
The problem with cuts on the paw pads is that they are constantly being re-traumatized when the dog either walks on them or licks at them, so they never really have a chance to form a good solid scab. And of course, without a scab to provide the lattice work for the pad to rebuild itself, it can't heal.
If this were my dog, I'd take her in to the closest emergency vet tonight for some sutures. They'll likely use a local anesthetic (like lidocaine) to numb the area and then put in a few stitches. Once they're in place, they'll bandage the foot and provide you with both antibiotics and pain medications to help her stay healthy and keep her comfortable.
I hope this helps.
Thanks for the info!