OR

you can move unused data to different filegroup and put that filegroup in another drive. (Putting onto same drive where you already have operation mdf file, will affect performance).

You can filter out the tables which need to be archived then create archive tables and move old data into that(like if table is employee then archive table is Arch_Employee).

I think its easy to manage.

Edit:-

Also you can filter out your archived table not to be replicated.