What is the chance for Apple to terminate my developer account? I've published a B2B iOS app in Appstore. When I submitted an updated version of the app, Apple rejected it as my app uses a background mode which is not actually required. But I justified the reason of using it and resubmitted the app once again. However, Apple rejected again. I've also contacted "Apple Developer Technical Support" and they are helpless :( 

Now, I hear from some of my co-developers that submitting app and getting rejected for few times may lead Apple to terminate my developer account. Is there any chance for this to happen? Please advice.Thanks!
Unless your App has; an un-announced hidden mode (tethering for example), or use any one else's IP - there is little likelihood of you being terminated for good faith App submission.

Common reasons for rejection are now listed here;
https://developer.apple.com/app-store/review/rejections/

If you are being rejected for these reasons, then you can rest assured that you will not be terminated.  If these were reason for terminations the forums would be flooded with complaints.  As it is, most terminated devs fall foul of complaints from IP holders.

Top 10 reasons for app rejections during the
7‑day period ending August 28, 2014.

14% More information needed

8% Guideline 2.2: Apps that exhibit bugs will be rejected

6%  Did not comply with terms in the Developer Program License Agreement

6% Guideline 10.6: Apple and our customers place a high value on simple, refined, 
creative, well thought through interfaces. They take more work but are worth it. Apple sets a high bar. If your user interface is complex or less than very good, it may be rejected

5%  Guideline 3.3: Apps with names, descriptions, or screenshots not relevant to the App content and functionality will be rejected

5%  Guideline 22.2: Apps that contain false, fraudulent or misleading representations or use names or icons similar to other Apps will be rejected

4%  Guideline 3.4: App names in iTunes Connect and as displayed on a device should be similar, so as not to cause confusion

4%  Guideline 3.2: Apps with placeholder text will be rejected

3%  Guideline 3.8: Developers are responsible for assigning appropriate ratings to their Apps. Inappropriate ratings may be changed/deleted by Apple

2%  Guideline 2.9: Apps that are "beta", "demo", "trial", or "test" versions will be rejected