Other than dog parks/hiking places, have you taken her to other public places where she'd encounter other dogs? Like outdoor malls.
Magnus gets overly excited sometimes and he'll lunge at other dogs. I pick him up and hold his muzzle softly but firm enough where he won't bark. I turn so he can't see the other dog anymore. If the other dog is still visible I'll turn around when Magnus stops barking. But if he barks again, I turn around again too. There were few times where he wouldn't stop so I just kept him held till I heard him sigh. Which I'm told is a sign of him giving up. Seems to be true b/c he behaves after that. Then comes the treats and praises.
It was bit hard the first few times out but after that, it got a little easier and Magnus showed improvements.