The new products, which are being rolled out between now and March, include ready meals, lunchtime snacks, bakery treats and chilled desserts.
They would give consumers "more flavourful and exciting, yet better-for-you" food options, said the retailer.
The existing recipes had been overhauled to improve their taste credentials by "going back to basics", added Alexandra Williams, brand manager for Be Good to Yourself.
"We have used more authentic and traditional recipes across the portfolio," she said. "For example, we now use flavoured stocks to create a stronger taste profile."
Other changes include the implementation of nutritional standards for fat, saturated fat, sugar, salt and calories to ensure the products have at least 30% less fat than their standard equivalents, or contain less than 3% fat overall.
Brighter packaging has also been introduced highlighting the recipe improvements.
Sainsbury's has also reduced the packaging across the range as part of its ongoing initiative to save more than 39.5 tonnes a year a 33% reduction.
The new look would help bring new and younger consumers to the brand, predicted Williams. "Since our last relaunch in 2006, the diet health market has moved on a lot," she said.
"This month's relaunch brings the brand into the next decade. Today's health-conscious consumers want more taste and more exciting dishes and won't compromise too much when choosing healthier options."
The relaunch would have a "very positive" impact on sales of the Be Good to Yourself line-up, she added.
New dishes in the 230-strong range include Thai Green Curry, Prawn Primavera, Sticky Toffee Pudding, Raspberry Panna Cotta and Tiramisu.
When it last relaunched the 11-year-old brand in 2006, Sainsbury's introduced its front-of-pack labelling system on pack.