sim neural network with imbalanced data

Hello,

I have imbalanced data and I want to classify it. I undersampled the data and trained Neural Network with this balanced data and I get a high success. I used patterned () for training and for testing the code is sim().

I want to be able to use this NN in real life and when i used sim() for it the result is really bad as this data is imbalanced. When I make equalize the number of the two groups the result of sim() is really good.

The problem in real life we even don't know the label of the data and i can not equalize before simulation. Is there any way for me to use this NN in real life for imbalanced data?

I would be very happy if anyone has an idea about it.

Thanks.