I suppose I should be able to figure this out myself with a bit of mathematical effort, but instead I decided to ask you folks! :-)

The interest I pay on my loans is not affected by the variations in interest rates AFTER I take out the loan, I am guessing? Meaning the interest is fixed after you confirm the loan, based on the interest rates at the time you took it? Correct? And if so, I suppose it could be worth checking if refinancing works out better when the interest rates are lower?