In this manuscript we tackle the optimal upgrade of an innovative optical transport network architecture called the Petaweb, which has a particular composite-star infrastructure that allows two-hop communications between edge nodes. Prior studies of the same authors have tackled the design and dimensioning problem for the Petaweb assuming TDM/WDM equipment and adopting a dedicated path protection strategy. A quasi-regular topology, more efficient than the regular, has also been proposed to minimize the quantity of fiber to install while preserving the regularity of the architecture. Exploiting the same network model, we propose an upgrade procedure for the extension of an existing optimized network, having one of the two possible topologies, under traffic increase and edge node addition.