just play more. the more you play the better your indurance gets.
No question, as far as endurance, don't forget to fuel your body correctly. And that doesn't mean Powerbars, or junk Carbs. Not all Carbs are helpful to endurance, and an abundance of Carbs will only turn to fat if not used.
The only other tip I give people playing is buy the most expensive equipment you can afford. Now that is a pretty blanket statement, but the point is, the better your equipment the better you can function on the ice. The lighter skates, or the better protection offered, or the quicker release from composite sticks, etc. All of these items can, and will improve your game, while offering significant support, and protection. This doesn't mean you need all top of the line stuff, just that there is significant, measurable gains to be had, in each level of better equipment.