Software for mobile phones I have wrote will do this in near future. (At the moment there is no mp3 support but you might get it as Christmas gift if I have time to implement it).
LucidWeaver dream alarm clock can be programmed to give a sound cue at every sleep cycle.
In near future you can record your own voice saying your own name like “Ollie you are dreaming!” and put it to LucidWeaver to be sounded as Dream alam at your personal sleep cycle peak.
Please check the topic:
[url]Lucid dream software for mobile phones - #15 by lucidweaver]