Nutrient that helps with leaf production

[#1Plantboy]

Is there a nutrient that helps with leaf production/ growing new leafs?

Thanks

[Slaphppy7]

Any nutrition, natural or artificial, will grow plants and the leaves of those plants.

Any particular plant you have in mind?

[#1Plantboy]

My bacopa australis and alteranthia renekii lost some leafs .

[madagascariensis]

Slaphppy7 is correct - all nutrients are required to some degree for a plant to grow. However, in a plant that is otherwise not deficient in any nutrient, nitrogen will tend to encourage the growth leaves over say, roots and flowers.
Keep in mind though that you won't ever regenerate leaves dropped naturally from the lower portions of the stem, as stem plants only grow new leaves from the shoot tips.