What Ryan said, except the puppy pads. I never got those to work. My puppies just liked to shred them instead.

4 months is really too young to 'get it', despite the fact that she would be physically able to hold it for a while.

First off, you need to get rid of her pee smell in your house. Dogs like to go where they went before. So, when you see her sniff, she is looking for one of her spots. When you clean it up, use an enzyme cleaner like 'Natures Miracle' (petco and petsmart have those) to get rid of the smell. Even though we humans cannot smell it, doesn't the smell is not still there. The puppy WILL smell it and use it as its bathroom again and again.

Then, start over and consider her not housebroken at all. Crate her when she cannot be completely supervised and/or only allow her roaming access in a limited area (kitchen for example - use baby gates to keep her confined). Keep an eye on her at all times. Reward her BIG time when she does go outside, so she associates puddle on the grass with reward, she will want to do it again. Piddling outside must be sooo much more fun and worth it for her than piddling inside!

Some people train their dogs to ring a bell when they need to go outside. Basically what you do is take its paw to ring the bell everytime you go out to piddle with her. She needs to associate the ringing of the bell with piddeling outside. I have not personally done that. My last dog would just sit in front of the door, waiting for someone to notice him - when he wasn't noticed, he'd piddle in front of it (which was good because it was wood - easy cleanup).
Here is a link about training a dog to use a bell: http://www.clickersolutions.com/arti...setraining.htm
Ringing a bell, though, means the puppy understands that it should be going outside vs. inside. As long as she finds opportunities to go inside, she won't really 'get it'.

When she does come back from outside and goes inside pretty much straight away, did you make sure she went outside? If she didn't go outside, don't take her back in until she did her business. Do not make potty break a fun thing in the sense that you allow her to play. It should be strictly business until she did her business - then its rewards and fun galore.

Finally, make sure she goes after meals, after naps and after a little play session. Those are the times they always have to go and won't want to hold it until later.

Raising a puppy can be tremendously frustrating (like when mine ate my ottoman and my custom made jaccuzzi cover), but so is raising a child and in retrospect it never seems that bad. Plus, for every frustration, you have a really fun memory.