gilt not coming into heat

I have a gilt that stood real well in the spring, I AI'd her and watched and she never came back in so I waited for the time for her to farrow and it never came. I put her back with the other gilts and have watched her and she has never shown any sign of heat. I would like to get a litter out of her, so what would you suggest that I do.
thanks for your time Gary

well i had a gilt do the same thing to me and i ended up just putting her with our boar and he teased her till she came in to heat and got covered. other breeders use matrix others just don't mess with her and cull them out of the herd. the only suggestion i can give you and i hope it works out for you is shoot her up with matrix and just wait to see if she comes in to heat.