Get back Release/NOC from current employer

Hai
I am working in Doha as an Accountant with my present company almost 4 years.While i reached to doha i was in Business visit, provided NOC from Business Visa sponsor to my Current employer for Visa transfer without exit qatar.Now i need to shift my job with another company in qatar for my wealth.There is any option available in Qatar law to get back NOC/Release from current employer for change my Visa to new employer ?
Any experts can please give answer regarding this .
anybody please answer for these !