You can increase your Neopet's level by doing Kitchen quests and Light Faerie Quests. Another way would be to feed your Neopet Cool Neggs. You can also train your Neopets at the Training School on Mystery Island or at the Swashbuckling Academy. Just make sure you select the course in Level. If you have a map to the Secret Lab you can use the lab ray to increase your Neopet’s level. Also, you may occasionally get a level for a Neopet as a Random Event! Beware though; some of these things like the lab ray can have other effects.