i took an order for 3 weeks ago for an event on November 8. My client ordered 100  simple rosette cupcakes so i quoted her a price. then this past weekend she texts me to change the order and add small  gum paste rosettes to the top of each one. So naturally i increased the price due to the additional cost and work for me. Now as of last night she messaged me again to drop the number of cupcakes to either 60 or 75. My question is do i keep my last price for the lesser amount of cupcakes or do i need to drop the price to match the cupcakes. I know i undercharge form y pieces anyway, i'm just unsure what to do in this situation. I am just getting back into taking orders so i haven't made up my order forms or contracts yet. Any advice is helpful please.  

So is it 60 or 75?  Good grief, who orders anything like that?  If you have not as yet specified when changes can no longer be made you should make the price match her number of cupcakes and then tell her the last date you will accept any changes. Oh, and make sure you get final payment weeks before the due date.  Let this order be the reason you get your contract details worked out quickly!

i don't know i have another observation -- i would make a fondant rose instead of gum paste -- gum paste can be eaten but it is by and large inedible -- fondant on the other hand stiffened with cornstarch would make a lovely great pretty chunk of crispy chewy candy especially if you add some flavoring like raspberry oil --

but decor on a cupcake should be edible if possible in my opionion

Has she hired you yet? That means, has she put down a deposit and signed a contract yet, not has she called you about it and had a price quote yet. If she has signed a contract there should be terms on it about the latest date to make changes. If that date hasn't passed then she can still make changes to quantity etc.

If she hasn't hired you she's not a customer yet, so you can either choose to continue to give her price quotes, or tell her that you're not available for her date if you think it's going to keep on like that.

What she said ^^^^^^^^^^

Sounds like the "potential" customer wants to keep her total cost around your first quote, so she back pedaled on the number she was ordering.  That's fine, but you do need to give her a firm cut off date for changes.