For sure.
The new monthly repayment amount and schedule will be based on the 700K loan.

When interest rate is low.
Eg.
Last time you sign up a housing loan of fixed 7% interest rate.

Now interest rate is 5%, you refinance it, to repay all the old loan of 7%, and start a new one at fixed 5%.
The 2% interest cost saving can mean a lot over the long term.

Refinancing may incur additional documentation fee, range from lawyer fee, admin fee, or old loan penalty charges etc.

Bank always reassess the repayment ability of the borrower.

Refinance - Last time you bought house with loan 350K (now appreciates to 700k), you refinance at the outstanding 350k, generally bank won't be questioning too much.

But if want to refinance at 700K, aka extra 350K cash out for other usage, for sure, bank will need to re-evaluate the debt service ability of the borrower as outstanding borrowing escalated from 350K to 700k, and monthly repayment amount escalated too.

Bank get the valuation through registered property valuer, whereby there is fee needs to be paid, if one interested to get the exact market valuation.
Alternatively, one can roughly know the valuation of property if one knows recent transacted price of your adjacent property of similar type and similar location.

Generally, market value - transacted/transact"able" price in the market at time being.