I do not usually say to chuck a batch of soap, but I think even I would start over. If you have chunks of lye leftover the bars will be high superfat and what it the chunk in inside the bar where you cannot see it when cut? If you try to rebatch them you will not know how much more lye to add and no the undissolved lye will Not dissolve in the the batter. It is water soluble.
If I do not use the split method, which I usually do my method of dissolving the lye in frozen purees or milks is as follows. I do use frozen milk or puree, I put it into a pitcher that I can really stir in without splashing and put the container into an ice bath in the sink. I then add the lye a spoonful at a time or sprinkle small amounts stir this until it no longer has lye stuck on the frozen cubes. I keep doing this until all is stirred in a dissolved. It a little tricky since you cannot see through the milk or puree, but if stirred well enough it should be dissolved. With milks you can get some saponification started and will see specks of soap. Doing it this way will cool it down considerable so still very well. You can then run it through a strainer while pouring into the batter, but you very well may just strain out some little soap bits. Of course the safest, if you are not comfortable in knowing if all is dissolved is use the split method as Toxikon explains above. The 50/50 method does not necessarily mean the batter will not darken when the lye heats of the batter, but it will not burn. Soap as cool as you can still keeping the oils clear.