Maria Mills, 51, was originally awarded Â£1,100 a month from 50-year-old Graham Mills after 13 years of marriage.
Appeal Court judges also ruled he should pay her Â£1,441 per month as she is "unable to meet her basic needs".
Mr Mills had argued he should not have to "pick up the tab" 15 years after the couple split.
Lord Justice Longmore and Sir Ernest Ryder heard the couple married in 1988, had a now-grown-up son, separated in 2001 and divorced in 2002.
Mr Mills, a surveyor, had agreed to give Mrs Mills, a former Notting Hill estate agent, almost all their "liquid capital" when they divorced, while he kept his business.
His barrister, Philip Cayford, told the court Mr Mills, who now lives in Guildford, had since remarried and wanted to "move on" with his life.
The court heard Mrs Mills had made some "unwise" property investments, moving from a house in Weybridge to a flat in Wimbledon, and then to an apartment in a luxury Victorian mansion block in Battersea.
After selling the Battersea flat she was left "without any of the capital", the court was told, and was now living in a rented home in Weybridge.
Mrs Mills works for two days per week as a beauty therapist, the court was told.
Frank Feehan, representing Mrs Mills, said she had been left with the responsibility for the couple's young child and without enough money to buy a house that she considered "good enough".
He said his client was "unable to meet her basic needs".
In the ruling, Sir Ernest said Mr Mills had the ability to make the increased maintenance "until a further order of the court".
The ex-husband of a woman who was awarded Â£230,000 on her divorce has been told by the Court of Appeal he must support her for life.