[xsl] Translation of values inside variables XSLT 1.1

Hello List,

I've a variable and want to change all values inside this from one specefic
value to another one.
I tried something like this

<xsl:variabe name="dest">
	<xsl:copy-of select="translate(source, 'V1', 'V2')"/>
</xsl:variable>

but it did'nt worked out.

Does someone know how I can change Values inside a variable?
Thanks for any Help!!

Jan