Before I got injured this year I was generating a lot more power then afterwards. I was doing hill repeats in the saddle pushing a big gear, strength work in the gym (leg press, squats, etc) and focusing on form (trying to eliminate dead spots) It made a huge deal for me right off the bat. I was doing weights twice a week and my hill repeats once a week, a dedicated work out to cycling strength.

+1 on the hill repeats. Find a hill with a decent grade that will take you 7-8 minutes to climb (somewhere in the ballpark of 1.5 miles). I like to spend a minute out of the saddle to work on passing speed, but the rest of the time I'm parked on my rear grinding out in a mildly uncomfortable gear. I'll do 5-6 repeats twice a week, or even three times if I have to cut my long ride short. After 4 or 5 weeks, you'll be very surprised at how much power you take into the climbs and how much better you feel at the top. I strongly advise a good cooldown spin after repeats and the ever-popular ice bath to cap it off.