LilyLover
You don't mention what type of lilies you grow, but after five years, most lilies will indeed need to be divided as they will be very crowded, so I think replanting is a good idea. However it's better if you move them to new soil and plant something different where they have grown. Rotate your crops, so to speak. Many pathogens build up in soil over time if you grow only one species intensely.
As you mention dry ground and living in a forest I do wonder if perhaps you have tree roots growing in your beds? In my experience one need either to use some sort of root barrier or dig through the beds from time to time. This would be another reason to redo your beds. Also remember that this years performance to a large part is decided by last years growing season as the food is stored in the bulb already.
That said I think that the more detailed info you provide on your growing situation, the better answer you will get
. Pictures help, too. Remember that we haven't seen your lilies or your beds and perhaps there also is problems with diseases and so on and there are folks here that are very good at diagnosing those things. But generally speaking I think digging and dividing would be a really good thing. Also of course you may need to water and fertilize a little more than you have done.
