Then best rejuvenating fluid I've found for strings is a product called K9P available from good music and engineering supply stores. Be sure to ask for it by name and explain what it is for.
I've found Elixirs good but they are not for everybody. They will hold the sound they start with, whether you like that or not, for much longer than uncoated strings.
These days I tend to use Newtones on most instruments as Malcolm Newton will supply them in custom gauges for the different instruments I play. They are well made and last well. I use Savarez Alliance HT regulars on my electro-classical after a long search for classical strings I really like.