How can I this girl to give me a chance?

I met her at this music festival about four weeks ago now, we made out a lot and she gave me her number and said we should meet up so ive started texting her and said do you want to come to this gig she said she couldn't because she had a bbq to go to. I text her again but have become less frequent and I am always the one who starts the texting so what should I say to her to get me back in?