It comes after a series of rate increases by the Bank of England with base rate now standing at one per cent.
Almost half of borrowers increased their loan size in April, according to LMS, with an average monthly increase of £208.
More than half of borrowers took out a five-year fixed rate product.
The figures suggest homeowners are looking to lock in borrowing as mortgage rates rise.
More than a quarter said the main aim when remortgaging was to release equity in the property.
The average remortgage loan amount in London and the South East was £320,400, double the £151,635 average for the rest of the UK.
Instructions of remortgages fell, but this is likely to be due to the timing of Easter, according to Nick Chadbourne, chief executive at LMS (pictured).
He said: “We always see a drop in instructions over the Easter period, especially since it fell near the start of a new quarter this year.
“We will see this increase again as consumers are looking to make savings in light of the cost of living crisis and continued base rate rises – they are likely to look for competitive fixed rate products, especially in the run up to the next ERC date which we expect to be in late June or early July.
“As such, lenders need to continue working closely with suppliers to assist people in finding the right products for them. Collaboration will be more important than ever to ensure further demands on market capacity can be mitigated and handled efficiently.”
