Randall, who opened his eponymous restaurant at the hotel on London's Park Lane after leaving the River Cafe in 2006, told BigHospitality the time was right to make some changes to keep the business fresh as it faced increasing competition from a growing market.
"When we opened 10 years ago there were lots of restaurants, now there are thousands in London," he said.
Plans for the restaurant, which shut its doors on Monday (4 January) for six weeks, include giving the interior a more modern look and making more of the bar area which will now be the main wine service area and the private dining rooms.
Design consultancy SuperFutures has been employed to lead the refurbishment which will include making the room lighter by removing the brown leather and dark wood pillars and installing a Terrazzo floor. Bare wood tables will feature as well as a new Kitchen Table with views into the kitchen.
Randall said he also wanted to increase the flexibility of the private dining with the introduction of a sliding door between a 25 and 40-cover room.
"Private dining is really important to us. It's something we've worked on for years, but we've been getting more requests for different uses and we wanted to give a greater option to those looking for a larger space," he said.
Changes are also being made to the menu, with the addition of a new bar menu and a daily changing lunch menu. However, Randall, who remains an investor in ASK owner the Azzuri Group, said the style of food would not change.
He said: "We have to be careful, it's not broken, so it's not a case of fixing it. Most of the dishes will remain - I've been talking to people for the last six months and they don't want us to change things. We'll just be moving on from what we do doing and offering great quality produce.
"We're planning more of a daily changing menu at lunch with good value dishes as well as a la carte dishes. Lunch is one of those markets where you've got to be flexible and be doing something different."
Secret to success
Randall believes the secret to the business's 10 year success was 'consistency' and 'promotion'.
"When you start a restaurant it's never perfect, you have to develop it and get a good amount of custom," he said.
"What's been great is we've had some really great customers, but we also work very hard on the restaurant and on the PR and marketing. When you've got your own business you have only yourself to push it.
"I think I work harder now than when we started to promote the restaurant. We still do Taste of London every year for example.
"The main thing is it's all about consistency. I'm in the restaurant every night, but it's not just about the food, it's about the whole experience. You have to ensure it's all great."