Antonyms for the phrase "easing up on" could include words such as tightening, intensifying, hardening, escalating, or increasing. These words suggest an opposite action to the idea of easing up, indicating a movement towards more control, pressure, or restriction. The antonyms of "easing up on" convey a sense of a firmer hand, stricter standards, or more intense levels of activity. Choosing the right antonym for "easing up on" will depend on the context and intention of the speaker or writer, as well as their desired effect and tone.