A couple of things you can do. First thing is to make a copy of your work and play around with that rather than the original and only!. Then select the dots by whatever method works for you, and go to Selection > Save Selection. It may come in handy.
Go to Object > Transform > Transform Each. Set Scale Horizontal and Vertical to a reasonable maximum percentage, above or below 100% depending on the general trend you want; click on Transform Objects and on Random. Click Preview. If you like what you see (doesn't have to be perfect, you can repeat the process or go in the other direction as often as you want) click OK.
Another possibility is to use a randomizing script: there's one at vectorboom.com, freebies, that allows you to set both minimum and maximum percentages. If you're not used to using scripts, you'll want to read the Illustrator Help information. If it's confusing, please come back for assistance.
Peter