exclude articles, not category

[pienso]

I'd like to exclude many articles from one category, but this category has to be displayed in sitemap. Don't want to clik out each new article from sitemap.
Option 'Max. Articles per Category' from 'Xmap - Content Plugin' isn't good, bacause there are categories I want to show all articles from. Only one way I find out is to modify field 'excluded_items' from jos_xmap_sitemap table. But if there was a new article it won't work. Shall I add for example excluding for 200 articles more? Now in this category are few subcategories wieh many artciles +1000.
How can I do this? I can also modify files.