If the firm "No" and loud "ouch" don't work, you can try giving her a short timeout in her carrier for 5-15 mins. It will make her understand that this is not socially accepted behaviour and when you let her out she'll probably be more loving than before.
If she's doing this at night then it might help to give her a fun play session before bed so that she is in restful mode at the right time.
My ChloÃ© likes to sneak under the blankets to nibble my toes in the middle of the night. I started doing the timeouts and now she rarely does it. It meant me getting out of bed a bit but she got the message and now we all sleep better.
Hope this helps.