Silicone filler in the nasolabial folds
The superficial silicone may change over time if there is associated inflammation of the material. Use of another permanent filler may have the potential to aggravate the situation.
Lumpy nasolabial folds after silicone
You have a difficult problem in the lumpiness that has developed in your nasolabial folds after silicone injections. The lumpiness appears to be fairly superficial and Artefill would be injected into a deeper layer. The Artefill could help to lessen the fold but I do not think it would improve the lumpiness. I think that surgery would be the only option to completely remove the lumpy appearance. The fold itself would need to be excised to remove the lumpy part and ideally, you would be left with a smooth line down the nasolabial area instead of the lumps.