Merge Replicate, reinitialise with a different part of the data I have a set of database with merge replicate configured between them.

The publisher is an aggregate of three sets of data.
Call them set 0, 1, and 2

There are subscribers that grab one set of the data depending on their geographical region (in SQL terms the HOST_NAME()).

One of the servers was setup with the wrong set.  (0 instead of 1).
I have corrected the function responsible so that servers should now get the correct set.
What do I need to do to force that server to dump its current data and grab the correct set all over again?

Marking the SQL server for a reinitialise from subscription did not do the trick :(
Please follow the steps in Create a Snapshot for a Merge Publication with Parameterized Filters to generate a new snapshot.  You must first generate a standard snapshot, then generate a Subscriber-specific partitioned snapshot.  After generating the snapshots, mark the Subscriber for reinitialization and start the Merge Agent to pull down the schema and data for the filtered subscription.