The ledger board of our deck is attached with nails only. One side is beginning to pull away. I put in more support posts so it is not separating further. What would be best to remedy the ledger situation?
Even if you've restrained the deck to prevent the ledger from pulling away more, I would be worried about those nails failing. If there's much separation between the ledger and the house you'll be putting bending stress on those nails. Is it feasible to add the lag bolts now? You haven't provided a picture or much description of the ledger area so it's hard to say what's practical, but I would say that getting that ledger securely fastened is critical to the safety of the deck.
Since this deck seems like it might have been a casual DIY job, you might also investigate the water membranes / flashing to make sure you're keeping moisture away from the house. Flashing may be difficult to retrofit but if it's missing or inadequate you should make an attempt to address that problem. Water can cause a huge amount of damage to both the deck and the house. There are several questions on this site that discuss ledger flashing.
If you can't properly secure the ledger to the house you might consider converting the porch to be free-standing, but that's a whole new project.
You have two options.
First, you can attach the ledger correctly with bolts or lag screws. Bolts with washers on both sides are preferable, but if you don't have access, lag screws can work as well if you are going into wood. In other materials, there are other methods you can use to attach.
Second, you can convert the deck into a free-standing one. To do that, you need provide appropriate support on the ledger side (you say you added supports - do you have enough of them and are they on proper footings), and you will need to provide diagonal support so the deck cannot move away from the house.