Meg, I don't really see anything wrong with this setup (we'll forget the overcrowding at the moment, it doesn't change anything in regards to breeding, and you are upgrading anyhow)....
Here is what I would do - feed them boiled, unsalted rice every morning, as much as they can eat within 10 minutes (yep, they get more in those times), or if you can time wise and are home, take those 10 minutes and do 2 morning feedings of 5 minutes each. Then in the later afternoon, feed them something high in protein. That can be frozen bloodworms, cut and mashed up cocktail shrimp (unsalted), frozen krill, daphnia, plankton, anything in that regard. Or you can make gel food with a higher protein content than usual and ease up a bit on the veggie part. Sometimes I just make a batch of food with hot water, gelatine and bloodworms...
Feed that protein, and as much as they can eat in 20 minutes or so. Do that, and do smaller water changes every 2. day (doesn't hurt, since they eat like the dickens anyhow), and then after a week, feed the same thing during the day, and then do a BIG Water change in the afternoon. Anyting above 50%, that is. Mine get even a 70-80% water change then.
Have a look at your weather while you do that - look out for either a low pressure system approaching, or the full moon. There is the theory that both of those systems are beneficial to spawning, even with indoor tanks. My first spawn happened after a thunderstorm, while the 2. one was after the most recent full moon. Then do the big water change on the day of the low pressure system/fullmoon.
If that doesn't do the trick, then I am out of ideas.....