@Nikita Krivets , I believe you can use the following PS cmdlet to create a new App Secret:
$startDate = Get-Date
$endDate = $startDate.AddYears(3)
$aadAppsecret01 = New-AzureADApplicationPasswordCredential -ObjectId {objectID of the registered application} -CustomKeyIdentifier "Secret01" -StartDate $startDate -EndDate $endDate
Do let me know if this helps. Also, if this helps in answering your query, it would be great if you can mark this response as "Answer", so that it helps others in the community too.