Yesterday, Acer started rolling out Jelly Bean update for its Iconia Tab A701 tablets, which apparently removed superuser (Super SU) access for all root apps. You can gain full root access by rebooting into fastboot; unlocking Acer A701 bootloader and then install the image of Jelly Bean (Android 4.1.1). Before following the below given steps, make sure you have Android SDK installed on your system.
Step 1- download the image of Android 4.1.1 from here
Step 2 – Reboot the device. 4.1.1 will start. Reboot it again to fastboot (adb reboot bootloader).
Step 3- Unlock the bootloader (fastboot oem unlock)
Step 4 – Install the 4.1.1 image (flash-JBRoot.bat)