I cold approached a shy girl 2 weeks ago from my college. She was showing strong IOIs and she accepted to go out on a walk with me, so we exchanged numbers. The following day I invited her to a dance social over text but she said "thank you so much for the invite, but I can't make it tonight. Hope you have fun", then I followed up with "no problem, are you free tomorrow to ___" but no response. This was two weekends ago. I'm going to try inviting her to lunch on campus one last time to see if it works.

My question is, how many times should I persist in asking out a cold approach lead?