All twelve-month regiments had to re-muster and enlist for three years or the duration of the war; I believe the act require a three year enlistment but the units were given credit for time already spent in service, which for most amounted to about 1 year credit.
A new election of officers was ordered;
Men who were exempted from service by age or other reasons under the Conscription Act were allowed to take a discharge and go home; and
Officers who did not choose to stand for re-election were also offered a discharge.
The reorganization was accomplished among all the Arkansas regiments in and around Corinth, Mississippi, following the Battle of Shiloh.
I think this reorganization affected the following units:
1st Arkansas Infantry.
1st Arkansas Mounted Rifles
2nd Arkansas Mounted Rifles
2nd Arkansas Infantry.
4th Arkansas Infantry
5th Arkansas Infantry.
6th and 7th Arkansas Infantry.
8th Arkansas Infantry.
9th Arkansas Infantry.
(Powers) 14th Arkansas Infantry,
13th Arkansas Infantry.
15th (Northwest) Arkansas Infantry Regiment
15th (Josey's) Arkansas Infantry.
19th (Dawsons's) Arkansas Infantry.
3rd Confederate Infantry.
24th Arkansas Infantry.
25th Arkansas Infantry Regiment.
I would appreciate any corrections or additions to this information!