I suppose you mean xp when playing a map
Most maps give you at least one tree, one lava bucket and one water bucket. That is more than sufficient to get unlimited experience. Lava and water gives you unlimited cobblestone. Tree gives you unlimited wood. make charcoal in furnace for unlimited experience. Convert cobblestone to stone in furnace for unlimited experience. Convert stone to smooth stone for unlimited experience. So you need a lot of furnaces to continuously gain experience. Use the final smooth stones to build all the future structures you require