Continuous deployment

[AshLucifier]

First deployment is successful but after that if i want to make second deployment i need to update the image tag manually then run the pipeline so that it can fetch it or if i use the latest tag it is not picking up as there is no change in deployment file.
can you please help in either changing the tag from deployment file or adding kubectl apply command as i tried using below but it says kubectl not found.
stage('List pods') {
steps{
withKubeConfig([credentialsId: 'mykubeconfig']) {
sh './kubectl apply -f k8s-deployment.yaml'
}
}
}
jenkins file working code.txt