The process you refer to, renewing their vows, is really called convalidation or, colloquially, blessing the marriage. Priests will typically only do this in a very low-key affair with only the bride, groom, and two witnesses present. I am not sure by a Catholic ceremony she always wanted she means a full-blown grandiose wedding with all the trimmings; if so, she may be disappointed, because it likely won't be allowed, presumably to encourage people to marry only in the Church.
She should be aware that the Church will not recognize her impending marriage at all until such time as it is blessed. As such, she will be in an irregular situation with the Church.
The good news is that simply being married by a non-denominational minister won't prevent them from having their marriage subsequently blessed. After all, the process is designed to rectify this very situation. If she got married by a priest, there would be no need to get their marriage blessed.