Welcome to the Porch, Steve.

But now I  see that I should have glued the base
because with all the planing the base has  become loose.
 Is there some way that I can keep it solid without gluing
it  together?  I know about the drawboring, but I would
 rather be able to take  it apart if I need to.

There are several options, although drawboring is
reversable with a small drill. Anyway, the easiest way to
make a disasebleable bench is with bed bolts.

http://www.leevalley.com/hardware/page.aspx?c=1&p=40445&cat=3,40842,41269

These are both easily removeable and can be cinched up when
the base loosens - more likely with changes in humidity and
aging of the timbers than with the stresses of planing.

There's lots more information in links from my Knowledge
Base, specifically:

http://www.jlatech.com/rob/Woodworking/Knowledge%20Base%20Workbenches.htm

Good luck, and happy surfing,

Rob in Peoria
------------------------------------------------------------------------