You need to set up a routine here. Walks at certain times of the day, take her out and walk her endlessly until she has a poo, plenty of praise. Put her out after every meal, upon her waking up, first thing in the morning/last thing at night. Go out into the garden with her when you let her out each time, rain or shine, keep an eye on her and do not let her in until she has had a poo, then once she has gone - lots n lots of praise. It will be slow process but you must be patient and consistent, dont give in, she will learn again to be clean in the house, good luck.