Not 100% sure what you mean? like you want to auto upgrade an ability of a unit if hes in the middle for a span of time like a king of the hill type game? Just make a trigger that will have a timer that counts the amount of time the unit was in the middle for and if the triggering unit is still in the middle upgrade the ability for that unit.
Heres a quick example, theres more to it than this though.
Code
Untitled Trigger 001
Events
Unit - A unit enters (middle map area)
Conditions
((Triggering unit) is A Hero) Equal to False
Actions
Wait some amount of time with a timer or just the simple wait
If (All Conditions are True) then do (Then Actions) else do (Else Actions)
If - Conditions
((middle map area) contains (Triggering unit)) Equal to True
Then - Actions
Unit - Increase level of Command Aura for (Triggering unit)
Else - Actions
also your going to want to make sure it does a check that the ability is less than the max level so it doesnt try to upgrade it beyond what its capable of.