I am using the following with corrplot:
corrplo
require(\"corrplot\") ## needs the corrplot package corrplot(cor(lpp_axis1, lpp_axis2), method=c(\"number\")
You could try changing the point size of text with par. I think the default size is 12. Adding a line like par( ps=14) before corrplot should make the text larger.
par( ps=14)
corrplot