One of my girls (Mimi) ears never stood up and she's 2 years old. I love them like that because she still keeps her puppy look. I could never imagine her with her ears up...gives her character. She's a big girl too...11 lbs
My males ears stood up at 14 weeks and my other girl was a rescue..her ears were already up. I noticed that Mimi's ears are much thicker than the other two so maybe that was the reason they never came up...I also didn't tape her ears. My thing was if they were meant to come up they would on their own.
I would try to shave and tape them to see what happens.