Hi,
I think this depends on the size of the database and the complexity of your replication.
If you can, it's best to remove replication, make the changes and republish. But this would need distribution of a new snapshot...how quick that is depends on the size of the database/publication.
If you can update publisher and subscribers so that they are still in synch after all the changes (and there are no changes happening on the database), you can add the publication with a no-synch option. This would mean and new snapshot would not have to be pushed out.
HTH
Graeme