If want to rate CDRs in Neon then please follow below steps:
1) Enable CDR ReRate against the billing gateway and select Rate Format
2) Assign Rates to the Account
if you want to re rate already imported CDRs then Go to -> Billing -> CDR. Search for the CDRs make sure you have selected Gateway in the filter.
At the top you will see CDR Rerate button click on it. Job will be logged.