Hm no, it won't remove the timer I guess. So the way you wanna use it, it would be a bad solution :s
My suggestions:
1)Dont use expiration timer, use a timer insetad (you will need to create variables)
Aktionen
Countdown-Timer - Start Timer as a Once/Unique timer that will expire in 60.00 seconds
Countdown-Timer - Create a timer window for Timer with title Spell
And dont forget desroying timer window if unit dies before, or it stops this ability.
2)You could just create floating text Timer (60) above unit, and then change the text every 1 second to "Timer - 1"
3) You could replace old unit with new unit (old life and mana). But if you do this with hero, he would lose all items. So you would have to put items variables before you replace it, and re-create these items after you replaced hero.