First of all, there is no such thing as CVT engine. CVT word is related to transmission, and not engine.
Well, I am not an expert, still, I would suggest to have a look at your car's CVTF. It might be needing replacement / flushing with new one, or CVTF level might have dropped.
Have your CVTF changed and transmission serviced, if not done already. It might resolve the issue.