More than half of buy-to-let mortgage cases in the first quarter from intermediaries were for landlords looking to remortgage, the data showed.
This is a sharp increase from the same period in 2015, when less than a third of buy-to-let cases were remortgages.
Around 60% of landlords looking to remortgage said it was in order to find a better interest rate, with just a third reporting their wanted to raise capital.
Paragon noted this is a significant difference from three years ago, when equal numbers were looking to find a better deal or to raise capital.
Brokers reported seeing a fall in the proportion of applications from first-time landlords over the same period, dropping to 13% from 19%, while the number remortgaging in order to raise funds to expand their portfolios has also reduced from 39% to 22%.
John Heron (pictured), managing director of mortgages at Paragon, there are a host of factors behind the surge in landlords looking to refinance currently.
He continued: “These include the expiry of the initial term on mortgages taken out ahead of the stamp duty changes for second properties, the expectation of rate rises on the horizon and a desire to minimise interest costs in the face of new mortgage affordabilty rules.
“It will be interesting to see the extent to which mortgage applications for purchases and portfolio extensions increase once these factors have played out.”