One little question about leblanc

So I have quite a few games played on leblanc, I think it's pretty safe to say I know what I'm doing on her (and I know my shortcomings as well, for example my cs is quite lower than average around the 20-25 minute mark which is something I am trying to work on). But there's one little thing in her kit that I'm not sure if it's something I'm doing wrong or if that's just the way it is. When you toggle her ult, is there a way to untoggle it without either casting it or waiting for it to toggle off? Sometimes I will hit R, but then immediately have second thoughts about what I was going to do. The problem is, then I am forced to use my ult to mimic one of my abilities even if I'd rather not, or at least pop a clone down, or else be stuck for a few seconds unable to cast any other abilities while I wait for the ult to untoggle on it's own. It feels really awkward sometimes. Is there some way to untoggle it that I've been missing all this time, or was that just designed to bring up the skill cap a bit?

Maybe I should give an example... So let's say I cast an e, but I missed, so I go to mimic intending to throw another chain, but unluckily a minion steps in between us. Now my options are limited to using mimic to distortion away, even if my actual distortion is off cooldown I'll be forced to waste mimic since I can't untoggle it.