As an early adopter of this feature, I can recall the numerous hours saved because of this feature. It is Generally available now.
When you enable replication, The replication dataflow extracts Salesforce data to build intermediate, locally cached datasets called replicated datasets. So every time we use or create a new dataset the user default dataflow transforms data in the replicated datasets and loads it into the new datasets.
Salesforce Wave Replication is not enabled by default. You can enable Replication from Setup > Wave Analytics > Settings. Select Enable Replication.
Please test this functionality in a sandbox before moving to Prod.