How can I get my fiance to wear makeup?

I really need some help with my relationship. I love my fiancé very much, the trouble is, sometimes I am not very attracted to her. Let me explain. She is a beautiful girl, but she just does not accentuate herself by wearing makeup. Just for comparisons sake (and not to sound shallow, but just to illiterate a point) I would rate her looks at a B+. I would rate my looks at an A (I work out a lot, eat very well, keep very active and dress nicely). So when she really dolls herself up she looks great, but it’s not that often. The thing is though that there are other girls out there who flirt with me who are better looking, dress nicely and wear makeup. I do not want to be with those girls though, I do love my fiancé and I do not consider myself to be shallow, I really am a nice guy. I just wish my girl would try harder for me. She looks amazing when she wears make up and she told me she feels more confident when wearing it. Then she says that she would rather sleep in the morning and that it takes too much time to do makeup. I am always very positive with her and tell her she looks great when she does wear it. I even gave her a gift of a facial and makeup consultation for our anniversary. I even told the girls at the spa to show her a quick daily routine. My fiancé went to the spa treatment and said she got a lot of constructive ideas and had a great time. She looked beautiful when she returned home and I of course told her that she looked gorgeous. She did put make up on the next morning. I thought my plan had worked but the next day…no makeup. The day after that…no makeup. I brought it up to her and said “what no makeup today?” She said “no, I feel like I am wearing a mask”. I said “would you like to try some more sensitive make up for your skin if it is irritating you?” She said “no, makeup is ok but only on special occasions; I don’t want to wear it every day.” I tried being positive and telling her that I noticed that she smiled more when she has it on and that there is a spring in her step when she wears it and that she said herself that she feels more confident with it on. I even told her that it is important to wear it because of the SPF content because the area that we live in is very sunny. I did not dare say that I wanted her to wear makeup so I could be more attracted to her. In the past I have even told her that I have dated girls who are not as pretty as her, but that carry themselves well, dress nicely, and wear makeup. After all of this she still has not taken the hint. It’s not like I want her to wear a ton of make up like that scary lady from the 1980’s Tammy Faye Baker, I just wish she would make more of an effort day to day. Please tell me any suggestions you can think of. I am out of ideas, at least tactful ones. Help!