________means adding, modifying or re-developing the code to support changes in the specifications

The term you're referring to is typically known as "code refactoring" or "code modification."

Code Refactoring: This process involves restructuring existing computer code—altering its internal structure without changing its external behavior. Refactoring is undertaken to improve nonfunctional attributes of the software, making it easier to understand, maintain, or extend. This might include renaming variables for clarity, breaking down large functions into smaller ones, or eliminating redundancy to enhance performance.

Code Modification: This broader term encompasses any updates made to code, including bug fixes, feature enhancements, and adapting to new requirements. Modifications may involve adding new functionalities, changing existing features, or removing outdated code.

In practice, both processes are crucial in software development, especially in response to changing specifications or user feedback. These practices help ensure that the software remains relevant, efficient, and maintainable over time.