As David Ebbo commented that you could leverage the Kudu WebJobs API about Set the schedule for a triggered job as follows:
PUT /api/triggeredwebjobs/{job name}/settings
Body {"schedule": "0 */2 * * * *"}
What is the recommended way to update the schedule? The preferred approach is to use PowerShell.
You could leverage the following command:
$username = "<username>"
$password = "<password>"
$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f $username,$password)))
$contentType='application/json'
$data= @{
schedule='*/30 * * * * *'
}
$body = $data | ConvertTo-JSON
$apiUrl = "https://<your-appname>.scm.azurewebsites.net/api/triggeredwebjobs/<job-name>/settings"
Invoke-RestMethod -Uri $apiUrl -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)} -Method Put -Body $body -ContentType $contentType
Moreover, you could refer to this similar issue.