Her clitoris will become VERY sensitive just before orgasm. It gets to the point where it is painful for her clitoris to be touched. That will be a good time to move your fingers somewhere else.
Teasing is also a good technique to break the continuous stimulation. You can bring her close to orgasm and then move your hands somewhere else like her thighs or breasts or kiss he before continuing. If you do this a few times she will react much better.
It is also important that you let her know that she is in control and that you will only do what she wants you to do and that she should feel comfortable with telling and showing you what she wants. If she tells you that she had an orgasm, you should not doubt her. Women react differently when they orgasm and she will be stupid to lie to you.
You can also encourage her to show you what she likes by her masturbating in front of you to orgasm. You should note how she likes to touche herself and how fast and hard she moves and where she stimulate herself close to orgasm.