Is there an income limit to the 501(c)(3) status?

I belong to an organization that is chartered as a 501(c)(3) organization of volunteers at a hospital. We are set up to accept donations to provide support to the organization, which allows us to put on special gatherings on special days through the year, and the balance would be donated to charities. Due to changes in management and the neglect by hospital director's office, the volunteer activity dwindled over a period of time, and we no longer achieve our donation income.

My question is this, how long can we keep our 501(c)(3) status without donations coming in?