It being over a month since your first date means she has low interest. My response either way would be the same, but my decision on whether to pay for anything would be different.
As a man, I expect to pay for a woman who *I* invite out, and it's easy for me to do that. Nothing fancy or expensive needed, but a couple of drinks on a first date. Maybe drinks and some appetizers on a second date. Whatever. But that's if things are progressing normally.
On the other hand, a woman who takes over a month to agree to a second date with me and does it with the "potentially" joking stipulation of free food is absolutely not going to get free food from me. And honestly I wouldn't be pursuing a woman that long anyway - would have generally moved on to greener pastures before then. But either way, my response to her would be the same and that would be to joke about it.
Her "I'll go if you're buying"
Me "Oh sure babe, I have a coupon for Boston Market. I'll get the mashed potatoes and you can have something of equal or lesser value."
And I'd take her somewhere free and if the date went well I'd at most buy her one drink.
Her "Haha funny" = No response from me
Her "Haha funny. But seriously where are we going to dinner?"
Me "Wherever you're buying babe! I'm into equal rights so figured you'd want to pay this time."
Her "What?!"
Me "Alright, well, you know what it's going to take to get me out on another date so let me know. PS if you are looking for ideas, I like pasta"
It is possible that she felt you were too much of a nice-guy type after your first date and is looking for more masculinity. When women feel that way, if they still engage you at all, it's usually to try to see if you'll stand up to them so they can confirm their assessment of you. You can be light-hearted while also standing up to them and this is the route I go early-on because it's better for my mindset and happiness, and it communicates I have control of my emotions and don't get upset over small things.