In order to answer this question you will want to first address the following issues. This may or may not be a hard question for your church to answer but the links below can help in seeing many points of view.
The church will need to have it's vision established.
A planning committee should attempt to find out if most of the congregation is willing to stay/move with the church's building.
The current site is a good or poor location.
The building is in good or poor shape.
The current building has space so we can grow or not.
The church has land to expand or not at the current location.
Zoning for the repair/expansion of the current space/building is in place or not.