ENTPs do like their pretty thought baubles but their needs go beyond their fleeting fixations, she also has romantic needs, friendship needs, physical needs and emotional needs.
Romantic: This is going to be the really important one for you since you're an INTP and we tend to suck at this, basically don't stop dating her. Have plans to take her places (even if it's just a picnic on the lawn) send her messages maybe 1-2 a day to let her know you're thinking of her, make food for her, surprise her with little gifts. I'm not saying you have to be her slave or spend a lot of money, it's the sentiment that matters, let her know she matters to you and be consistent about it because even confident women need a lot of reassurance.
Friendship: Being romantically involved with someone doesn't mean you stop being their friend, keep hanging out, having fun, telling jokes, etc, don't be too serious about being in a relationship.
Physical: Everybody likes food, and sleep, being warm and a good solid fucking. If you can be attentive to her needs such that she doesn't need to ask you for things she will adore you for it.
Emotional: Also a tricky one for INTPs, then again you're a man so it's not your job to get all worked up and emotional about things, that's what she has female friends for, no your job is to be there for her, listen to her, be a shoulder to cry on, etc.
In summary don't worry about keeping her entertained, if you're an INTP and she's an ENTP you will burn out long before she is satiated, consequently ENTPs are pretty good at finding or making thier own entertainment, rather the challange for you is going to be to maintain your enthusiasum while she bombards you with her thoughts and ideas.
Focus on being her boyfriend (or whatever) rather than a shiny thought bauble, because she will burn through a dozen of those a day, rather you want to be that source of stability and comfort she returns to.