How to avoid lack of dots in reference title?

I am using Export-Filter_Editor_Linux_64bit_V04b to customize the reference style. I am using the nbib format to populate my bibliography, but some titles have a final point whereas others do not.
In the bibliography style, I have placed a “.” after the field, but in that case, some titles have double dots. Without the final dot, then there are some titles without dots.
Is it possible to set a dynamic point so that the dot is placed only when it is missing?

For such things, you can modify your jstyle file with the replace formatter. See Custom export filters - JabRef → Replace(regexp,replacewith) Replace("…,.").

I think the JabRef documentation for export-filters may be a good starting point for many of your questions.