Do you need to refinance a home loan to add ayour partner to the put your partner on the mortgage?

Sure do.

Yes, b/c that person has to credit qualify in order to be on it.

Why would you want to do that without a refi? It would not lower your rate. If you just want them on the deed then just add their name, but if you want them on the mortgage you might think of a good reason to do so other than just because.