To clarify and expand on it a bit: What was renewed/changed only three times so far is the capability set of the Bundeswehr.
Basically, between 1955 and 1963/64, a plan was drawn up "how to fight the Soviets". This plan would demand certain capabilities - along the lines "we need FACs for the Baltic Sea, we need close-support aircraft, we focus the army on mechanized combined-arms forces, we implement a helicopter-insertable paratrooper force" and so on.
This plan was then, subject to the budget, put in place over the next 10 years, and kept like that until 1990. Of course there were changes in how to implement it - add a division here, cut the FAC plan from 60 to 40 there, change the organization of home defense and give them some extra spare equipment from the field army, build a new MBT to replace older equipment, and so on. Adaption to external restraints. But the overall plan stayed the same.
In 1990, the Bundeswehr suddenly had to first absorb another military, and was - together with that - then cut by 50% until 1993, as demanded by the 2+4 and CFE treaties. By 1993, some capabilities had therefore been cut completely (such as elimination of CAS aircraft, or SRBMs), and a transitionary capability set had been enacted; this included formation of some non-specialized light infantry units already btw, and also of course a shifting of units into East Germany, and giving up the "defense belt"; first attempts at entering into peacekeeping were made.
By 1995/96, the first plans were set up to approach a future capability set for the Bundeswehr; first, dedicated special forces were added on larger scale, then brigade-scale infantry units were implemented. The Kosovo War and subsequent occupation added some experience. A number of capability concepts were played with for a while here and there, until the MoD sat down and had it all compiled and hammered out between 2001 and 2003 into a definitive structure (the "Concept of the Bundeswehr").
Which is now being implemented. Unit-wise, the change will be complete by next year, for the next ten years after that, proper equipment for that new structure will keep flowing in (much like was done in the first ten years after 1963/64 - set up the units first, keep using old or transitionary equipment until the ordered proper gear is there).