Merge Replication: Updates to Schema

We have a main SQL Server which replicates to two backup servers via continuous merge replication.

There are regular updates to the schema. Regular changes include:

1. Adding new tables and relationships with existing tables
2. Changing the data type of columns on tables already replicated

What is the easiest way to maintain replication in such an environment?

If changes are made to the publisher, some changes cannot be synced to the subscriber and the whole replication has to be setup again (agent + subscriptions).

These databases are too big to replicate in its entirety every time there is an update.

Any advice will be appreciated.