Can I Use Excess Loan Money for House Upgrades Post-Sale?

I live in my sister’s house, but she’s not interested in it because she doesn’t live nearby. The house is worth $225,000, and I asked for a $375,000 loan to make some upgrades. The lender, CalVet, wanted to know how much my sister wanted for the house. I said $275,000, and I planned to use the remaining $100,000 for upgrades. However, the lender insisted that the upgrades must be completed before the sale closes, which my sister refused to do. I’m new to home buying, so I’m unsure if I can get the extra money from the loan as cash back for upgrades after the sale.