Final answer:
The main purpose of maintaining progress evaluations is to review goals, assess their achievement, and set new goals for the future.
Step-by-step explanation:
The main purpose of maintaining progress evaluations when an off-the-field evaluation has already been completed is to review goals, assess whether they have been met or exceeded, and set new goals for the future. By conducting progress evaluations, program managers can determine the effectiveness of the program and identify areas that need improvement. These evaluations provide useful and usable information that can lead to program enhancements and improved outcomes.