In this case you shouldn't tell her too bluntly cos it may be
hurtful for her, if she feels inadequate in the uhm lacy
stuff.
What I think is that you can recommend her some brands and styles
casually. Like - hey you'll look good in this. But nothing
drastic... no fancy lacy stuff, just simple cotton designs that
she'll be comfortable in.
If you're looking for smaller-cut bras , you can check out the
teenage lines like Bee Dees, or Pierre Cardin.
But ultimately if she refuses to change, you gotta accept
that.
