I'm not sure exactly what you are asking, I'm not sure what you mean by "without losing pixels".
To export a RAW photo as a RAW, you would select Image Format to be "original". When you do this, the RAW image is unchanged by your editing; the editing you have done appears in a sidecar file and only certain Adobe software can make use of it. You could also select TIF or DNG depending on your needs, and if you don't resize the photo, you don't "lose pixels" (in fact, Lightroom never "loses" pixels)
Choose the file format you want under File settings in the Export dialog.
If this is for printing, use tiff, or jpg with quality set to 100%.
If you want a full size image, uncheck Resize to fit.