CHM File Size

I am working for a software company as the documentation guy and use RoboHelp a lot. I'm on version 7.00.145 and I noticed that the size of our .chm file is over 100mb and keeps getting larger. I also noticed that the pictures within the help file are .bmp which are fairly large. I've been going through making all .bmp pictures to .jpg (a much smaller one). After about a third of the way through, I generated a new .chm file and the file is much larger than it was before. Are the .bmp files still in the .chm even though I have replaced them and deleted them in the main folder? Any help on this matter would be much appreciated. Thank you!