ok i'll give you a hint, the reason why you d/c for melee mobs is because there is a cmp ( compare ) command that checks weather or not the mob is attacking, with your godmode on you have it so it doesn't register as hitting you. but the cmp causes you to d/c because you are saying the attack isn't registering but the mob is still attacking. so to remove the 15sec limit on melee mobs you must change the Opcodes just above the address that controls Collision so that No Collision doesn't cause d/c.
Sorry if thats confusing, it's early in the morning and Im not sure how to explain it. but if the above confuses you. Simply Find the Godmode Address then look at the Opcodes of the addresses just before the address that controls godmode. Read those Lines and Fix them to match what you are doing