Quick question regarding overflow pipe.

I am installing a new bathtub and need to raise my overflow pipe two inches. It is a PVC pipe. I tried to raise it last night but it would not move. I did not try real hard because I noticed that would prbably crack if I used too much force. I have no idea what the previous owners glued it with. Any suggestions or advice?

picture is a thousand words. Can help without it.

If it's pvc it's glued with pvc glue. The only way to raise it 2" is to cut it and glue a new 2" long piece of pvc pipe with a pvc coupling fitting.