Its hard, to catch up with language. I started a program for toddlers in San Diego for this reason so my kids could learn to speak now not as adults. http://www.jenniestarr.com/ivrit.htm
I have to say for me though as an adult, I’ve tried Hebrew Online listed already and am a fan. They do a great job. The teachers I had were terrific, the classes are real-time so even though you’re in your room, the teacher, the other students are online with you. You get called on to read, you talk with other students. The teachers even write the words others are saying on their white board to help you phoenetically and in Hebrew so you can follow. I was very impressed. Just bummed when they couldn’t accomodate a later evening class 8:00 pm for us in CA.
My classmates were from all over the world, which was nice.
Here’s a link to my summary of the experience with Hebrew Online as well as a link to a San Diego ulpan if you’re in the area . I’ve heard good things about it, though the methods are a little unorthodox. http://ivritbivrit.blogsome.com/category/adult-ulpan/
The other key is of course finding ways to communicate with other people in the language. This is really tough to do outside of Israel as your community may not have what you need. Gatherings with Hebrew activities. I created a bunch in San Diego because I couldn’t find it. http://www.jenniestarr.com/chevratyisrael.htm But, for teenagers especially, what you need is a real Tsofim I think to make it work. Some cities have them, others don’t.
Listening to radio and TV in Hebrew is great too. I don’t have links handy, but if you can tolerate not understanding a lot its still a great way to learn; reinforce what you don’t know and gain new words.
