I have noticed that already active spells are not affected by perks and effects that modify spell magnitude

For example, casting Oakflesh, it gives 40 armor, I add a perk that double spell magnitude by 2, it's still 40, but after the effect end and I recast it, the spell gives 80 armor. Then, if I removes the perk, it stays 80 until the spell end.

Is there anyway to make these effects scale with magnitude while they are active ? I do have alot of spells in my mods that have durations of 1 or even 2 days.