For many reason we reconfigure the SharePoint Development or PoC farm. I had SSRS configure on my Single server farm initially. Due to some issues i had to recreate the farm by running the SP configuration wizard. 

After new installation i was trying to setup SSRS on SharePoint 2013. I was not getting the new service application creation option though the Reporting Service and the reporting service add-in was already installed.

After some heart burns i got to find that my SSRS service was in disabled state. In these scenarios you dont have to re-install, rather run the below ps script.

$si = Get-SPServiceInstance -all | where {$_.TypeName -like "SQL Server Reporting*"}
$si.status <-shows you the status, if it's disabled run: