It sounds like you are on the right track with following the same routine every night.
A set time to go to bed every night may help your toddler to expect sleep. If toddlers get over-tired, they may have a harder time falling asleep, wake up more during the night, and even wake up earlier in the morning. Find out what time your toddler naps at day care as toddlers who nap later may need a later bedtime. The key is to watch for those yawns that signal he's getting sleepy. If he kicks into "overdrive" mode, his body will be pumping out adrenaline, and getting him into bed will be much harder.
Starting the wind-down process early in the evening may help your toddler to unwind while providing a sense of security. Try diming the lights an hour before bedtime as part of your routine.
Check the amount of sugar content of food your toddler eats in the evening, and make sure he gets enough fresh air, sunshine and exercise during the day.
All in all, it is quite normal for your toddler’s sleep routine to regress at times.