HELP! Wild Puppy!

I have a 8 month old Chocolate Lab who we cannot get to settle down when other people or animals enter the picture. She obeys pretty well the first time or two using the clicker and treats, but then totally ignores us and goes her own way - jumping on people and running off with whatever distraction (i.e. other dogs) come her way. She seems to have gotten wilder in the past month. We take her for at least 1-1/2 hour hikes/runs everyday (sometimes twice a day) so she is not a dog desperate for exercise or company. She just likes to jump and play - to everyone's dismay. She will only work with me and the clicker/treats for short time spans - then does her own thing. When we're so far from the house (on these walks) it's a dilemma how to "positively" deal with her so she "gets it". Any advice? I don't want a juvenile dilinquent dog. Is 8 months too late to break these habits that have arisen?