Upgrades...

i want to know how to make a ability used by a UNIT level-up via upgrade.
my units have neergy shields 15/1, and require the research (Shields). but the upgrade "Shields" has a level 2. "Shields 2". how do i make it so when i research "Shield 2", the energy sheidl 15/1 is automatically replaced by the "25/1 shield?

in fact i want all if my unit's ability to level up when i do a research. how is this possible?

there's another effect to upgrades that sets the level for an ability. you can't miss it.

tutorial on upgrades which should tell you all