How do you keep improving? A lot of the things I'm asked to sing are not difficult. I'm often repeating the same sort of task over and over again. But while repetition is useful for learning, there are other ways to help me improve.
Today I recorded songs that required me to sing rhythms that did not go well with the words. The timing and the pitch had to be perfect, in a way that is much easier to reproduce on a keyboard than it is with the voice. This was challenging. I often sing solo and can get away with modifying things a little for stylistic reasons, but not today. The work was frustrating and I did fail to sing everything perfectly the first time. But making mistakes is vital for learning. It's O.K. to get something wrong and then work to correct it.
There is an excitement in stretching yourself and finding that you can do something that seemed out of reach to begin with. Improving at any skill requires you to have a desire to learn and to improve. And singing is a skill. Many people talk about it in terms of being a "gift" or something that you are born with. People often say to me "that they would give anything to be able to sing well", but the thing they rarely seem to want to give is their time.
So pick a new song to sing. Something higher, or lower, or faster, or something so slow it requires amazing breath control. Find something that challenges you and get excited about what you can learn to do.