Another strategy is added value.
This is a widely used extension strategy. Large companies, in particular food producers, will slightly alter a product to make it seem new and attract new attention to the product. An example being a soft drink company producing a limited edition flavour of the product. This renews sales levels and gives the product continuing interest.
Along with the other options,companies can also look at new markets for their old products to extend the PLC, a classical example here would be Toyota's Qualis which was close to being obselete in its major markets worldwide was launched in india and turned out to one of the biggest hits, thus extending its PLC