Antonyms for the phrase "run low" could include "surplus," "abundance," or "plenty." When something is running low, it means that there is not enough of it left to use or consume. The opposite of this would be having more than enough, or having a surplus. An abundance of something means that there is an excessive amount available, while plenty refers to having a sufficient or ample amount. When it comes to resources, it's important to monitor and manage them carefully to avoid running low, but having a surplus or abundance can also bring its own set of challenges.