If you have had them for a year they have probably spawned already. if you dont have a tank set up special for spawning, i am afraid the eggs will get eaten, maybe this is why you have not seen any fry.
At a year old you should be able to spawn them under the right conditions. Things like conditioning with live foods, water quality/chemistry, & keeping your Tetras in a species tank (a tank with only glolight tetras in it, or maybe glolight tetras & some other docile fish e.g. otocats, cories) would contribute to success considerably.