The redefinition level seems to be the hardest level for most people to plan for with any regularity. As you'll see in this blog post, it's actually not that difficult or time consuming to redefine your use of technology.
In this blog post, you'll find four examples of a lesson modified through all four level of SAMR. It's helpful to see how SAMR is applied to lessons in different subject areas and to see how various apps can be used for educational purposes.
It's always good to hear opposing opinions so here's one argument for why the SAMR model can be problematic. This article brings up some important points to consider when using the SAMR model to ensure that technology integration is truly being done effectively.
If you're interested in learning about the nitty gritty behind technology integration, check out this dissertation. Dr. Bridget Abbas examines how teachers overcome challenges to integrate technology in low-income, ELA classrooms.