How to upgrade rooted Lava Iris 354E running Jelly Bean to Kitkat

This device doesn't meet the minimum hardware requirement to run Android Kitkat. Google has mentioned here:

Device implementation MUST have at least 340MB of memory available to the kernel and userspace. The 340MB must be in addition to any memory dedicated to hardware components such as radio, video, and so on that is not under the kernel's control.

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[The] /data partition MUST be at least 1GB.

In short, you should stick with your current OS, or buy a new device with better hardware specifications. Even if a hack is available out there to somehow run Kitkat, it's not worth considering the severe limitations on the hardware end.