Converting pc mp3 files to VBR

[MusicLuver2002]

I was wondering if it's possible to convert the mp3 files I already have in my pc music folder? The songs are 192 bitrate and would like to change them to VBR. Is this possible to do without burning them to a disk first at 192 bit rate and then re rip them to VBR?
Was hoping this is possible and not have to waste of bunch of disks.

[Spoon]

dBpowerAMP Music Converter, right click on mp3s >> Convert To >> mp3 (Lame).

You should know your new mp3 files will have less quality than the original mp3s, it is how mp3 works.