This maybe sound rude, but if she doesn't look intrested anymore, that maybe doesn't have to do with the dick... It could be you too, not everything is dick-related in a relationship and making love. Sorry if this isn't what you wanted to hear...
Though you have an excellent point, it does not answer his question as he's looking for advice on how to get that 'spark' and interest back, as misguided as his attempts maybe with PE's.
Before you read any of what is below, have you tried to express that you miss her playing with you in that fashion? She may think it's not a problem but you seem to enjoy it and want it back. Ask her if she wouldn't mind rekindling that or if there is something you can do to rekindle that urge to play? Often that will take it in the direction you want.
Has she expressed to you directly her waning interest in your member?
I think you need to look at your relationship man and focus less on your PE's. I'm not saying the issue is 100% relationship because I don't know your back story. It could be simply the novelty has worn off, and she's use to it. Not to say she's not turned on by you or your member! Or that she is into you less or loves you less, she's just been there before.
Ask your self could it be anything else that's going on right now that may affect her interest - stress, problems at home or work? Is there a riff or a fight between the two of you? Give it some thought and I'd be interested in hearing what you come up with.
Relationships fall into rhythms, maybe try something different, focus on other things in bed and outside for a while, try to get that urge back to play with your member in other ways.
Sometimes for me and my wife it's a matter of flowers, or a kiss on the neck that gets her into some sort of mood that rekindles a excitement into something we've done a few times before.
