I would interpret "rebaseline" to mean you want to replace an original
baseline with an updated one. Easy Peasy. Just save a new baseline over
the original one. That being said, be sure that's really what you want to
do. I think the baseline should be saved at the point you have finalized
the schedule for the project as you actually plan to work it and then leave
it alone. That way you can do meaningful comparisons between what you're
getting versus what you'd planned. Rebaselining looses that original plan
so you have no basis for compariosn. The exception to this is when there
has been a scope change that materially effects the nature of the project,
meaning what you have after the change is in effect a whole new ballgame and
you now need to track progress against the revised plan.