REPROCESSING UNSEALED JARS---
If a lid does not seal within 24 hours, the product must be reprocessed or stored in the refrigerator and used within a few days. To reprocess a product, remove the lid and check the surface of the jar. If there is any damage to the glass, the jar must be replaced. Reheat the product, if a hotpack is required. Pack food in clean, hot jars. Place a new heated lid on the jar and adjust the band. Reprocess the product using the canning method and processing time recommended by the recipe
Reprocessing Jam/Jelly that didn't Jam/Jel
On this forum, someone said this did work but I don't remember if they did jelly or jam with this process.My canning book: It says to measure jelly to be recooked. For each quart of jelly measure 1/4 cup of sugar, 1/4 cup water and 4 tsp. powdered pectin. Mix pectin and water and bring to boiling, stirring constantly to prevent scorching. Add jelly and sugar. Stir thoroughly. Bring to a full ROLLING BOIL over high heat, stirring constantly. Boil mixture hard for 1/2 min. Remove from heat. Remove foam from the jelly and pour at once into sterilized jars. Fill to within 1/2 in. of top. Process water bath for 5 min. Sure hope this does help you, and I sorta think it will work for jam. At least I hope so.