Just FYI the existing obligation doesn't have to be a home purchase loan.
From the Glossary of GIR:
A refinancing is any dwelling-secured loan that replaces and satisfies another dwelling-secured loan to the same borrower. The purpose of the loan being refinanced is not relevant to determining whether the new loan is a refinancing for HMDA purposes. Nor is the borrower’s intended use of any additional
cash borrowed relevant to determining whether the loan is a refinancing, though the borrower’s intended use of the funds could make the transaction a home improvement loan or a home purchase loan.
We're all here 'cause we've lost control.