Refreshing a playlist

Hi,
I receive a weekly show in 6 parts. Each part has the same filename every week, but the parts may vary in length.
I have created a playlist which calls up each part in turn, along with jingles, etc. to complete 2 hours worth of streaming. But next week my playlist may be longer or shorter than the required 2 hours as the parts will be a different length.
Is there a way to refresh the playlist to see how long the total is once the files for each part have been changed?

One of the ways is to save the playlist (to m3u8 file), then edit it in the notepad, deleting all lines starting with # - that is, leaving only file names. When you open the playlist in RadioBOSS, it will re-read the duration and other information from the files.