Assuming these are proper fruiting cultivars and not from seed, the main factor is to get them into good growth. Citrus flower and fruit in a continuous cycle rather than all at one time like apples or plums.
Even in a conservatory in the UK they are limited because of light levels and lack of warmth in winter, and suffer a long dormant period when they should be given the minimum of water.
In the spring, once frosts have finished, set the pots outside. Make sure they are adequately potted, but don't overpot. Sometimes all you need to do is to remove the top layer of compost and replace it with some fresh compost.
Use a proper citrus feed and make sure you water with rain water if you are in a hard water area.
Make sure they have good light levels.
If they are suffering from diseases like mealy bug, which is very common, treat the little 'bumps' on the leaves and stems with methylated spirits or a pesticide.
If the conditions are good, there's no reason they won't flower and fruit again.
Often when you buy a citrus tree at a garden centre it is already in fruit and the trees have been 'forced' in ideal conditions, or even imported from better climates.
It's not surprising that it can take them a year or two to adapt to ours again.
We bought a kumquat, a tiny citrus fruit, covered in fruit, but it didn't flower or fruit again for two years.
Treat your orange and lemon with care and it will reward you sooner rather later.