I am running my instrument under remote control and have taken a reading with a math function enabled. Is there a way to get the raw data without triggering a new measurement?

Yes, use the "SENSE:DATA:LATEST?" or "SENSE:DATA:FRESH?" queries. Either of these commands will return the last measured value that was processed by the math function.

The "SENSE:DATA:LATEST?" query will return the value as many times as the query is sent.

The "SENSE:DATA:FRESH?" query will only return the value the first time it is sent. If you send it again, it will cause a -230 error, which is "Data corrupt or stale."