But what does "better" mean? And more importantly, what should you be doing between now and the start of the season to get "better?"
If you're going to use the winter season to set goals, you should first know what constitutes an appropriate one. The right kind of goal is one that provides direction and enhances motivation.
It's important to set attainable, yet challenging goals, as you always want to stretch yourself to reach them. Easy goals don't require enough discipline to be meaningful and can end up promoting low motivation, resulting in minimal satisfaction. On the other hand, small, specific goals can yield big results.
All of this, however, presupposes that you know where you are and where you are headed.
Look at Your Ranking
At the end of each racing season, look back at your results and determine where you ranked against the field in each discipline (swim/bike/run).
Triathlon and duathlon race results provide easy feedback for this calculation. If you find that your bike split is consistently slower against the field than your swim and run were, then target that area for specific attention in your training.
Be careful to set your goal with a personal training focus (to build more strength on hills) and not based on how you finish versus your competition (to make the top ten at nationals).