Network providers aim to offer a high level of service quality in order to satify their customers' requirements. One of the key factors to fulfil this requirement is a careful network design providing enough available transmission capacity. As data traffic tends to increase continuously, network operators regularly face the necessity to upgrade their network to match the growing demands. In this paper, we evaluate and compare different strategies for deciding how many and which links to upgrade. Calculations for example networks demonstrate the efficiency of the strategies in utilizing the newly added capacity. Since optimization of the network's routing further helps to increase resilience and allows a more efficient use of the available resources, we include this approach in our evaluations. Additionally, the possibility to include anticipated failure scenarios during routing optimization is also compared to the other strategies. It is shown that the straightforward approach to upgrade the most utilized link is not necessarily the best choice. Instead, an optimized upgrade planning including routing optimzation can deliver a higher resilience at lower cost.