When you add something to a the rss filters that applies to an existing entry in the rss list you can not easily add that/those item(s). You can turn timer off, clear, then turn timer back on. However, that will only rescan things new enough to still be on the feed. If your altbinz has been running for days, it very likely has many more entries than the feed provides. If the item you wanted was older than the feed, but still in your list... you are sol for testing... and you will need to add it manually.
To solve this, there should be a 'rescan' button that is available whenever ANYTHING is in the list (whether timer is on, or off). When a user hits rescan altbinz should start from the top of the existing list (do not load rss again from server) and re-check every item, including older items that have already been checked.
This process should have two branches. The first branch, is for a previously red entry. If a red entry is found to pass, it should be marked green and downloaded (following existing settings) as if it just came in; if it fails again, leave it red, and move to the next line. The second branch is for a previously green entry which presumably has already been downloaded, or skipped/deleted. If a green entry fails with the new filters, it should be changed to red, maybe giving the user an optional warning; if the previously green entry passes again it should remain green but be skipped (not re-downloaded)... to avoid duplicate downloads.
I think this would greatly enhance the rss handling... you might also think about leaving 'refresh' available even while the timer is set. I have often hit timer twice (off then on) to reach this effect, but would be nice to have a single button.