How to play PCM sign wave (representing a DTMF tone) for a x duration (say 1.5 sec) again and again?

Question

I  have generated the PCM sign wave for DTMF (dual tone multiple frequency). However my requirement is to generate DTMF tone until user releases the DTMF tone key. 

Is there any way to contine to play the same x duration (1.5 sec) generated PCM sign wave (for a perticular DTMF tone) again and again? This is possible if you are creating the graph in the graphedt.exe tool and play it. It will play the same x duration generated PCM sign wave again and again.

How can I achieve it through programming? Looks like i need to set some property, not sure.

Thanks in advace.