Go about changing the length of an existing recurve design.  Would you simply lengthen the riser?  Lengthen the limbs only?  Riser and limbs?

Any and all assistance gratefully appreciated!

I really don't see how you would lengthen the limbs unless you built new ones. You could lengthen the riser to make the overall length of the bow longer, but I'm not sure what your trying to achieve? More forgiveness, more velocity, or more draw length?
I'm not a glass bow maker so I don't really have the answer, but I know some guys on here surely do. Just didn't want to leave you hangin out there with no replies.

Semo, thanks for the response.  And, in answer to the question, I'm after overall bow length with the intent of increasing draw length.  Just cant decide how to get there.

For me it would depend on how I felt about the bow prior... is it too heavy in mass weight? too light? are the limbs being used efficiently? stacking? overbuilt? underbuilt? also, how big of a change I'm lookin' to make, etc. I might get it a combination of ways. Stuff like that might help me decide how to approach the o.a.l. thing.

You didn't mention, is it a one piece or a takedown?

Are you changing a design you've already used, or modifying a set of plans for your first run?

Yes, it is a one piece takedown of an old Damon Howatt design (have the bow in hand).  It's a 62" recurve and I want to duplicate the profiles at 66" to allow for a bit more draw length.  Weights (stack) etc. I'll just wing it!

This bow, Like most Howatt designs is (was) an excellent design and a great shooter.  Unfortunately a kid closed a tip in a car door!  I plan to recreate the design in 62" (as is) as well as 64" and 66".