I almost always organize my photos by date now, using collections and keywords to find the images that I want. I use the format year/month/day.
Anyways, I used to organized them by day only or by location. I want to reimport my photos with all collections and editing data staying the same but move everything into the date format. Do I have to manually create folders and move these one by one, or is there a way to reorganize the folders as if I were importing these?
This is relatively easy to do.
Firstly make sure you save image edits to xmp, so data is with the image and not just in the LR catalogue.
Then if you use dumb collections make sure you can restore them.
Once that is done, remove images from catalogue and import them back in by date and restore your collections.
The fine details -
1 - To save to xmp if not already done so automatically, select all images and Ctl/Cmd+S. Better still make sure 'save to xmp' is turned on in Preferences/General/Catalogue Settings/MetaData and check 'save to xmp' - that way if a catalogue goes squiffy, then you don't lose any edits since previous back up and you can work in parallel with your images in Bridge no problem.
2 - Preserving dumb collections, simply select all images in each collection and give it a keyword that is name of collection [+prefix collection], so 'collection dogs', 'collection cats' 'collection birds'. So all you have to do to recreate collection is search for the keyword 'collection' and use the individual keywords to then refill your collections.
3 - When importing tell LR to 'Move' images and also tell it what date folder to place it into and do not apply any presets.
It may be easier to create the uber date folders, Year and Month outside of LR and if you know the rough dates you can place directly images into them when importing. Moving folders whilst in LR is painful as you can only do one at a time, so anything that reduces the folder shuffling is a good thing.
Alternatively, import all by date en masse [with minimal previews set], then remove them all from LR again and quickly and easily move the day folders into the correct Year/month folder in your file browser [explorer/finder etc] and then get LR to sync the top folder or reimport from top year folder.
I use the year/month/day/description folder structure and may have several folders per individual date as it can be easier to look through several smaller folders than one massive folder with a variety of completely different image subjects in it.
This means I can quickly scan through my folders and find images in any OS and using any programme.