Penny, make sure you wash the floor where she has pee'd really well to take out any trace of smell there - you can buy special products for this. She has just got into a bad habit and will take a bit of extra time and effort to break it. If it's a nice day like today take her outside and stay out with her until she has pee'd - it shouldn't take long for a young puppy. Praise her for going and then let her in - I would then take her out every half an hour for a while and watch her like a hawk. If she starts to pee indoors, scoop her up, telling her no and put her outside. If you keep telling her no and putting her outside, even if she is halfway through she will soon get the idea - it won't be pleasant for her being constantly interrupted when she is peeing. And if she is getting extra praise and treats when she goes outside she will soon prefer to go outside. Always wash the pee thoroughly. Young puppies don't always get it right though, it is more common to have accidents early on and your lucky if you don't. She will get there eventually.
