Refinancing based on appraised value before closing all cash deal

[James Denon]

I am looking to buy a short sale property. The bank that owns the house, claims the house appraised at 90K. They listed it 75K. My realtor tells me they already have a 75K all cash offer. 

I am willing to put 75.2K to beat it only if I can refinance for 90K and essentially get it for free since I would be getting around 78K back based on 20% downpayment and 90K appraised value.

Can I agree to offer 75.2K cash and get it appraised before closing and cash out re-finance the deal?

Maybe I tell the lender that I  will close with all cash at the closing. The next day, I turn around and refinance it for 90K.

Thoughts?