Yep, frequent cycling of the fan means low pressure in the coolant lines (lower than should be anyways). Buy a can of R134a at AutoZone/etc and fill it up yourself. There's instructions on the can. Just make sure you wear eye protection and fill on the correct side (low pressure side, I think?) You also might need more than 1 can if it's really low. Our A/C can hold 27 ounces and each can is 12-16 ounces. If you think the A/C is leaking coolant, you might get the combo R134a with sealant and/or dye. I had this problem until I recharged about a month ago. It's fine now even though I had a significant leak somewhere. (fingers crossed)
