Before you plan for improving performance, you need to identify what the gap in performance is so you can take the necessary steps to close the gap between the required and available performance levels. Once you have identified the gap, you need to choose your method of performance improvement, whether it be through training, internal or external resources, job enrichment, on-the-job training, or job rotation.
Therefore, please review the performance appraisal system you are using. On the other hand, make use of the search function to find more information on this site regarding gap analysis.
Regards,