Final answer:
The model depicting the pattern of cycling through stages of behavior change, with each cycle resulting in further progress, is a spiral.
Step-by-step explanation:
The model being described when mentioning that people often cycle back through earlier stages of behavior change but advance further each time they renew their commitment is a spiral. This is much like a spiral design process used in development projects where designs are continuously improved upon through iterative cycles. Each time a cycle is completed, the understanding of the design (or in the case of behavior, the self and the behavior) is deepened, and thus, subsequent cycles build on the progress made. The cycling and returning with greater knowledge or commitment represent an upward progression much like moving up the coils of a spiral.