Contracts end, and the work usually does not. When a contract's term winds down, the agency runs the competition again, and that rerun is the recompete. Because award records are public, you can see when contracts in your trade were awarded and roughly when they will come around again, which makes recompetes the most predictable opportunities in the entire system.

In a sentence

"This is a recompete of the facilities support contract awarded in 2021." The incumbent is warmed up; everyone else has been able to see this coming for months.