It's may be possible (but I haven't tried) that if you use EV-reducing berries then talk to the woman, she might say "it needs to work a little harder" again. Then when you max the EVs again she will say whatever she says after she gave you the effort ribbon last time.
If that doesn't work then no, you won't be able to tell aside from counting. However, if you're maxing out two stats then you can just keep battling the appropriate pokemon until you're sure you've got enough EVs.