To address all the things you've been ignoring. Things in training you've not been doing over the past year, like types of workouts, different warm-ups, testing new products, different bike position, new strength routine, your diet, new training group, new coach, or whatever else you think might need to be changed.
You can't wait until the middle of the season, it will be too late or too risky to see the benefit. If you're really interested in seeing what works, just change one thing. Pick the biggest need or what you're most motivated to change, and go with that. If you change too much, you risk injury, or not really knowing which one affected you the most, (positive or negative).
Make the commitment now, before it's too late to reap the rewards this season.