Would like to know what type of replication you have ?

According to BOL, Reinitializing a subscription involves applying a new snapshot of one or more articles to one or more Subscribers.transactional and snapshot replication allow individual articles to be reinitialized; merge replication requires all articles to be reinitialized.

Reinitialization occurs for one of two reasons:

You explicitly mark a subscription for reinitialization.

You perform an action, such as a property change( Alter a column or add a column or any schema changes to the articles invloved in replication) , that requires a reinitialization.