Remortgaging
Lenders provide a variety of packages for doing this. There are a number of reasons for doing this, one would be to obtain a better rate of interest and another could be to raise capital for any reason, the second one is generally described as "equity release" mortgage.
Typically you will be able to borrow up to a certain % of the equity in your home, given to you in a lump sum which you then pay back like a normal mortgage. This can be used to pay for home improvements, lifestyle changes, home repairs almost anything, really.