They are defined in the experience.ini. I added this for my Spider Lair to raise in level and it works.
Code:
;------------- MordorSpiderCave -----------------
ExperienceLevel SpiderLairLevel1
TargetNames = MordorSpiderCave MordorSpiderLair
RequiredExperience = 1
ExperienceAward = MORDOR_ORCPIT_LVL1_EXP_AWARD
ExperienceAwardOwnGuysDie = 0
Rank = 1
AttributeModifiers = BasicLevelUpProduction1
Upgrades = Upgrade_StructureLevel1
End
ExperienceLevel SpiderLairLevel2
TargetNames = MordorSpiderCave MordorSpiderLair
RequiredExperience = MORDOR_ORCPIT_LVL2_EXP_NEEDED
ExperienceAward = MORDOR_ORCPIT_LVL2_EXP_AWARD
ExperienceAwardOwnGuysDie = 0
Rank = 2
AttributeModifiers = MordorOrcPitHitPointModLvl2 MordorOrcPitBuildSpeedModLvl2
Upgrades = Upgrade_StructureLevel2
LevelUpFx = FX:MordorOrcPitUpgrade
End
ExperienceLevel SpiderLairLevel3
TargetNames = MordorSpiderCave MordorSpiderLair
RequiredExperience = MORDOR_ORCPIT_LVL3_EXP_NEEDED
ExperienceAward = MORDOR_ORCPIT_LVL3_EXP_AWARD
ExperienceAwardOwnGuysDie = 0
Rank = 3
AttributeModifiers = MordorOrcPitHitPointModLvl3 MordorOrcPitBuildSpeedModLvl3
Upgrades = Upgrade_StructureLevel3
LevelUpFx = FX:MordorOrcPitUpgrade
End
If you want more than one upgrade to happen when it levels up just add another entery here.
Upgrades = Upgrade_StructureLevel2
Upgrade_YourUpgrade