I've done this a large number of times. There is no "easy way" of doing it with replication in place. Basically the process is:
- Prep the new server for replication (setup the distributor)
- Get all apps using the subscriber databases offline
- Validate all subscriptions
- Resolve any validation errors
- Drop all subscriptions
- Drop the publication and disable replication on the publisher
- Backup the publisher DB
- Restore the publisher DB on the new server
- Make any changes you need on your database for and metadata relating to the old server to the new server
- Setup the publication on the new server
- Setup the subscriptions again WITHOUT INITIALISATION