hi Kabibi,
The point here is not how long does it take to reapply the VISA, rather it is the availability of VISA required. In your case, anyways the VISA is going to expire shortly. Consider pushing the mandoop of your present company to deal / negotiate with the govt. authorities instead of exploring the option to rejoin the previous organization. I am sharing the same with you basis my experience in HR in hospitality industry itself in Doha.
Trust that would help