The phrase "easing up" implies a sense of relaxation, reduction, or a decrease in intensity. The antonyms for "easing up" would be words that convey a sense of increase or intensification. Some possible antonyms could include "heightening," "escalating," "intensifying," "amplifying," "aggravating," "exacerbating," "augmenting," or "magnifying." These words suggest an increase in pressure, tension, stress, or difficulty rather than a reduction. For example, if you were applying pressure with your hands and then "eased up," you would be decreasing the pressure. Conversely, if you "intensified" the pressure, you would be making it stronger.