Hi Smgmaster:
Well you could pick out something for you and something for your wife, if she is also willing to assist in the “refueling”. Since you are already in an intimate relationship, you might go for Turn Up the Heat. There is an interesting thread about this from the female point of view: Turn up the Heat: OMG PLEASE POUNCE ON ME AND DO ME HARD ASAP!!!
If you feel like you and your wife don’t communicate well enough, and that this might be part of the “dimming”, you could try instant honesty, which would encourage both of you to engage in deeper conversations if either of you wears it.
In terms of a product for her to try, instant sexiness is a good basic choice. There are two versions, A and B. What kind of personality does she have?