Updating rooted device

[SF97]

Hi, I have a rooted Sony Ericsson Xperia Active with the android version 2.3.4 and I want to update it to android 4 and in order to root it I downgraded the firmwarefrom 4.0.2.A.0.62 to 4.0.2.A.0.42 and then rooted using a toolkit.
Now to upgrade to Android 4 how do I do it? Is it safe? Do I just unroot it and update it trough sony ericsson companion or do I do something else?
And if I have to unroot it how do I do it?

Thanks.

 

[sanchitgrover]

Y dont u just flash a rom which has android 4.0 as base

Ps i'm not sure if something like this exists or not