Anyone have any idea why my usually prolific lovebirds haven't laid any eggs for a long time,like almost 2yrs?

They're about 5 years old, some are younger than that. They were in a n aviary, reproducing a lot and then I took them into my house in cages so they'd be warm in the winter. That was approx. 2yrs ago and although I made certain they kept their mates, they don't seem to be interesred in having babies. Any comments?