I agree with Robyn. IF your females are just not going to ovulate this year, then they probably deserve a chance at some chow, so go ahead and warm them up.
You didn't say how old or how big they were before you started cooling them and pairing them with your male(s). You also didn't say how long ago you started pairing them. That kinda matters.
Another thing, if you've never felt developing follicles before, you may not know them if you are feeling them. Plenty of people visually miss the ovulation bulge and don't even realize it when they have a gravid female... unless you've been doing this for a few years, but it doesn't sound that way.
Just on the basis of general reproductive physiology - I would caution you against trying too hard or too often to palpate your females for developing follicles. No, it isn't documented (at least anywhere that I know of for Ball Pythons), but there is at least some chance that if you don't know what you are feeling for, or how much pressure is appropriate, you could harm your animals... or just their reproductive organs.
Just a note of caution.
You've gotten them this far. Calm down a bit and try to figure out what is in your animals' best interests. Several breeders have good information about cues to look for that indicate ovulation OTHER THAN palpating for follicles. Markus Jayne and The Snake Keeper both have very informative articles on breeding - and I'll bet ProExotics does too (their site just takes too long for me to load on my ancient computer and dial-up connection).
Good luck.
~Rebecca
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0.1 Dumeril's Boa '04 (Courtney)
1.2 Ball Pythons
[1.0 '05 Orange Hypo (Specter)]
[0.1 '05 Het Orange Hypo (Sylvia)]
[0.1 '03 Normal (Sue)]
0.2 American Pit Bull Terriers (40lb darling lap dogs:Brandy&Mara)