Do I need to pay her back the money she has paid so far?

I am a web designer. My client website was coded in a old language & I put it in PHP. Since I did not get the new site done in time because of the old coding, she said that she wanted the old site to be left on until their conference was over in Oct. We have been talking & she said in mid Nov. she would work with me to get the new site up. Now she is not wanting to do so even though the site has been ready for launch shortly after we talked. She wants her money back. Since it was to be launch in 2-3 months and it was not and she said to postpone it till after the conference and then she said not only 2 weeks ago, she would work with me and now she is refusing even though the site is done and ready to be launch. Do I have to give back the money because it was not launched in the original time frame? Even though she has agreed to postpone it in the past but now that doesn't seem to matter.