What a delightful problem to have. But a very real one. A million is never enough. The excitment of having the money leads people to develop creative ways to invest that money in the community. Soon the volunteers, the staff, and the neighbours discover the community has enough opportunity for good work that it could use two million.
Good works expand in proportion to always exceed the funds available.
The million will eventually be all gone. It may be a year. It may be a decade. But it will not last forever, no matter how wisely invested. Sooner or later you'll need a campaign again.