Replace letters on the whole page, but not within the tags

I've been searching for this for days.. but no result.

I want to replace latin letters with cyrillic ones using php. But I want to exclude some words and letters within the specific tag <notranslate>

So if I have:

<p><b>Ovo je neki tekst</b> i ovo sigurno <notranslate>nece preci u cirilicu</translate>, hvala !</p>

I want it to become:

<p><b>Ово је неки текст</b> и ово сигурно <notranslate>nece preci u cirilicu</translate>, хвала !</p>

How to do this, using regex ?