How to change every Nth character in Notepad?

Question

Notepad++

Before:
Example. Example. Example. Example. Example. Example. Example.
After:
Example. Example. Example (REPLACEMENT) Example. Example. Example (REPLACEMENT) Example.
You need to replace every Nth character with another. For example, a point is taken, can you help with how to implement this and how to increase the gap (here, for example, every third point is given, how can you do every fifth , seventh , and so on)?
Thank you.

Answer 1

Something like this (?:.*?\K symbol ){N}
Example for every third dot https://regex101.com/r/A7aQ0I/1
Option without \K https://regex101.com/r/A7aQ0I/2
Find: ((?:.*?\.){2}.*?)\.
Replace:$1 (ЗАМЕНА)