What you really need to do is say have a way to store your level, using numbers. Say, each block is stored in data statements.
data 4 ; block number
data 13 ; mesh reference number in array
data 20,10,0 ; position of mesh
data 13 ; mesh reference number in array
data 40,10,0 ; position of mesh
data 15 ; mesh reference number in array
data 35,10,0 ; position of mesh
You would have an array that you copy the mesh from, using the reference number in the data statement. That way, everytime you load a new block, you construct the block form the data statements which contain the mesh number and it's position. Create these new meshes in a type collection, so the time a new block rolls round, you free all the entities in it, then create the new ones.
data 4 ; block number
data 13 ; mesh reference number in array
data 20,10,0 ; position of mesh
data 13 ; mesh reference number in array
data 40,10,0 ; position of mesh
data 15 ; mesh reference number in array
data 35,10,0 ; position of mesh
You would have an array that you copy the mesh from, using the reference number in the data statement. That way, everytime you load a new block, you construct the block form the data statements which contain the mesh number and it's position. Create these new meshes in a type collection, so the time a new block rolls round, you free all the entities in it, then create the new ones.