You absolutely need to talk to your PD first. You can't switch programs without your PD's permission. Although you sign a contract from year to year, as far as the ACGME sees it you have a 3 year commitment to the program, and you cannot go to another program without the written approval of your current PD. It is likely that they will want you to at least finish the year because of scheduling constraints, and it will behoove you to do that since it may make it more likely for your PD to approve your transfer. Besides, the majority of positions to transfer into will likely be PL-2 positions to start in July, rather than trasnferring in mid-year, but it won't hurt to inquire. Hopefully your PD will understand (you're in pediatrics, so if your PD doesnt understand the improtance of social support and a mother's bond to her child, then the person isn't someone I would want to work for), and if he/she does, they can often help you find a position elsewhere. If your PD does not grant you approval, there may be an appeal process through the ACGME...hopefully it won't come down to that.
Next you need to find programs. I would just email PD's at any program that is geographically desireable and tell them why you are intersted in transferring. Ask them if they foresee any openings for a PL-2 spot (and if it came down to it, a PL-1 spot if necessary). Things change in programs often, they get approved for more spots, people leave for various reasons (specialty/career change, family reasons like you, residents fast track into fellowship, residents get kicked out for being incompetant or unprofessional), and programs are often left scrambling to fill the vacant spots. It is completely acceptable for you to inquire about this. I wouldn't feel as if you are "pleading" anything, because if a spot isn't available, "pleading" gains you nothing. You are merely inquiring about potential job openings and it is ethical, professional, and acceptable to do such.
Last year, we lost two interns from our class. One switched specialties, and the other's husband got a job in a new city. When our PD was interviewing residents to fill the vacant PL-2 spots, one of the most important things she looked at was the reason for transferring. Residents transferring for family reasons (as in your case) were given priority. In fact, one of the residents who transferred in initially was not approved by her original PD. Our PD eventually got him to rationalize a bit and made him realize how foolish it was to keep an unhappy resident whose husband was leaving for another part of the country.
One thing you must be cognizant of is that you did not match initially. It may help you to identify the reasons why this occurred. If there are red flags on your application, the program accepting you will want to know how those have changed over the past year.
Best of luck.