Only if you use a lossless codec such as Magic YUV, UT Video, Lagarith, etc. You can use other intermediates such as Cineform, XAVC, etc. and re-render with a a minimal amount of loss. It just depends on how many times you re-render and whether the resulting loss has any practical significance to you. You can also re-render delivery formats such as MPEG-2 or AVC, but the loss for each re-render will be greater and thus not recommended. Again, it all depends on how much loss you are willing to live with.
The key number here may be how "multiple" you plan on rendering (i.e. twice, 4 times, 10 times). If it's more than two or three maybe you could explain your workflow, then some of the more experienced users can recommend a better way of going (which may include nesting Vegas projects in other Vegas projects).