I think there is hope for up to 8 months old if they do show promise of standing around 4-5. Do her ears flop up when she's looking at you, one up one down? She's going through her teething stage so make sure that she is getting all the nutrients that she needs, I think it's calcium that goes down during the teething process, but I'm not entirely sure on that you'd have to check other posts on this. Rizzo had one ear up and one down at 14 weeks and by 16 weeks both were standing, for a couple months they would change up, until I shaved them down and now they stand like champs, and his ear hair is long and pretty, you can see it in my avatar
Good luck, maybe you should shave the hair a little closer to the skin, be very careful not to clip the ear though.