Because of your condition, I felt it necessary to put in an early reply! If a mole is precancerous it usually does not cause problems if the resection margins had been adequate and it was completely removed in all dimensions. Despite this, some cells from the mole might have remained underneath or there has been changes in the cells in the bed of the mole after the removal which has given rise to the swelling. The type of swelling you have described appears to be a neoplastic one or a new growth since you have described the lump as hard and growing in size.
Since you do not have the report of the earlier operation, the best thing that needs to be done is a complete removal of this swelling with a margin of 5mm-1cm all around followed by biopsy
of the same. I would not waste any time doing a needle biopsy of this swelling given your history of deep infiltration of the mole and the characteristics of the lump. However, the main thing is: ACT FAST!
Hope this answer helps you out!