The phrase "play catch up" is often used to describe the act of working extra hard to catch up on something that has fallen behind schedule or fallen behind in progress. There are many synonyms that can be used to replace this phrase, depending on the context and the situation. Some of the most commonly used synonyms include "make up for lost time", "get up to speed", "fall into line", "close the gap", "catch up on lost ground", "pick up the pace", "make progress", "gain ground" and "bridge the gap". By using these synonyms, you can add more variety and depth to your writing or speech and convey your message effectively.