Congratulations on your addition to your family.
I recently went through the same process switching a house-trained 8 month old to piddle pads. It took about 2 weeks to reach 100% perfect pad use. The change probably would have been faster had my older boy not guarded the piddle pads as his own.
Re-training is a lot like training a pup for the first time.
Limit Buttons' freedom in your home; confine her to areas where you can keep her under close supervision. Make sure she has quick and easy access to the pad at all times. Anticipate her need to potty and take her to the pad. Choose keywords like "go potty" to encourage her. When she does things correctly, praise her profusely and maybe give a small treat (I give one kibble). Never stop praising.
The first week, try putting about 4 pads down in one large square to enlarge the target area. My guy had no problem peeing on the pad, but he required a lot of convincing that it was okay to poop there too. I had to confine him to a small area lined with pads and sit with him until he did it. When he saw how happy I was, he finally understood what to do.
Hope this helps and that you have great success.