What’s a good comeback?

I want to ask a girl out from work. We have been talking for about a year. I asked her for her number but she gave me her IG instead. I asked her out about a year ago through IG for a baseball game but she said “ it sounds like fun but it’s my nephews bday.”

I want to ask her out again for a festival next month. If she says “I’ll think about it or I’ll get back to you.” Should I say “ let me know soon so I can ask someone else out”?
I don’t want to sound like I don’t have any other options. What do you think?

What’s a good comeback?
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