Well, if you push yourself you will get faster/stronger. But if you are relatively new to cycling you will need to experiment a bit on how hard you can go for how long. I prefer to go a bit easy for say the first half of the race/ride and keep enough 'fuel in the tank' for a strong finish. If you want to compete in races on a regular basis and become better at them then you might want to start a more formal training program to include intervals and hill repeats, as well as endurance mileage. Be sure to include rest days in the program. There are some good articles here that may help you.