There are several ways to bring fish into breeding condition, these are some which I have used, feed the fish with live bloodworm or frozen bloodworm, bring down the temperature of the water by a few degrees, this sometimes triggers off spawning. On the other hand fish like angels prefer the temperature to raise a few degrees. water quality is very important, a change of about a 1/3 a week should be OK for most species. Provide plenty of caves / pots in the tank for the fish to breed. As the fish are a breeding pair you should have no worries, nature will take its course and you will soon have the fish spawning in the near future.