Don't know how entrenched your dp's views are on not having another baby, scoobysnax. If he's simply dithering a bit, he might come round to the news of your pregnancy pretty quickly if he sees you are happy about it. Would you tell him it was an accident?
Does he like being a father? Is he into babies and toddlers, is he OK about the lack of sleep, the nappies etc? How he's coped with your first child is going to be a good indication of how he'll cope with another IMO.
But ultimately I agree with the messages that say be cautious about deceiving him.
I had to persuade my dh to let us try for another baby. We talked and he came round to the idea, and he certainly loves his youngest son. But it did put a strain on our relationship, especially in the first two years.
My dh did not want to go back to baby-and-toddler-land. He had given up his job when my oldest son was 2 and had studied while being his main carer until my son was 5. He enjoyed it at the time but felt enough was enough.
When my youngest son was little, I found my husband less supportive. He was working, granted, but even when he was not, I did all the nappy changing and if I needed time alone, I really had to twist my husband's arm before he would look after my baby son. He definitely felt some resentment even though he had agreed to us trying for another. He said because he loved me he had 'given in to my wish'. If I complained about my baby son he could say 'well this was your choice, now live with it'
It was only when my youngest son began to walk and talk that things got better. Even now, with my sons aged 9 and 3.8 months, my dh has a stronger bond with the eldest. Things are getting more equal all the time, now, but the early two years were hard. Even now, our family is often divided into two units - oldest son and dh, youngest son and me. My youngest son still has a stronger bond with me. My husband loves his youngest son, but admits he has a stonger bond with his eldest. And I think it will take years before the last vestiges of my husband's resentment finally go.
Of course, the age gap between my two sons didn't help at all. To my husband our happy, chatty 6 year old son (who adored his father) was much easier to look after than a 1 year old baby. As my youngest grows up, I am sure things will change, especially once my oldest enters puberty and possibley starts rejecting his father for a while.
If the age gap is not so great in your case, you may find things a lot easier, but if my experience is anything to go on, if you choose to get pregnant on purpose, things could be a bit bumpy for a while.