Unfortunately, you've missed the critical teething time so it's less likely that tipping the ears now will work. But as Silaria said, it can't hurt to try. I recommend using glue...it's easier on the dog and for you to do, especially with an older puppy. I like Tear Mender but hair extension glue is good too.
If you want to try something easier, get a bottle of pure glycerin from your pharmacy and rub some on the inside and outside of the tip. Bend it down and massage it once or twice a day. (Apply the glycerin about every other day.) That will soften the ear leather and encourage them to drop.
Good luck!