Actually, that should shorten her life span for she would live more than normal about 3, 4 times faster due to her power if she uses it.
Not really if you consider the extent of her power. She is able to affect 'space' thus she can theoretically slow her own aging by same method. She is a smart girl. I am sure she has found out a way to extend her life...
It doesn't change the fact that Remilia *will* outlive here either way.
