[Jass] Tome of Attack lost when transforming

[dracolich]

Is there any way to restore lost bonuses from tomes?
There are used spells, based on Metamorphosis, and bonuses from tomes comes from modified Tome of experience.
I tried to re-add tomes on transformation, but nothing changed at all -
UnitAddItemByIdSwapped() - didnt do anyting
UnitAddItemById() - same
UnitMakeAbilityPermanent - same
etc

Is there any way at all, except changing transforming base spell?