This may very well be easy for people who have been using powershell for a long time, but after a couple of weeks of use I was amazed by what I can achieve.
This will allow you to export current snapshot schedules on your volumes and then re-apply a different schedule WITHOUT modifying the retention times.
#Connect to a controller, get volumes from the controller, get snapshot schedules for said volumes, and export to a csv:
Connect-NaController Controller1 | get-navol | Get-NaSnapshotSchedule | Export-Csv -path d:\something.csv
#Import the csv reading in current values and assigning each column a label.
#For each object, create a new schedule by RE-USING 4 of the 5 available columns/data fields. Note how the Labels used are the current values previously #exported - hence the values aren't changed
import-csv d:\something.csv -header ("label1","label2","label3","label4","label5") | foreach {Set-naSnapshotschedule $_.label1 -Weeks $_.label2 -Days $_.label3 -Hours $_.label4 -Whichhours "1,2,3,4,5"}