Hi
As per my friends in Singapore,there are different catagories of job visas depending upon your qualification
if you are just a diploma holder in your profession than maximum you can stay 2yrs+2yrs extended job visa single with out your family ,than you have to reapply for job visa depends upon your company if they need you,if you are a degree holder in your profession than chances are good for you can stay with your family,for more years with facilities, so check this all details with your employer in Singapore
before you leave this job in Qatar
Bye