Here's how I would do it. There are other ways...

Save the scene you were just working on to a new file name - this will be your subsequent scene.

In the animation palette, make sure that all the cells of the final frame have a keyframe - select them all and click on [+] to create them to be certain.

With all the cells of the final frame still selected, grab them with your mouse and drag them back to frame 1.

Delete all other keyframes. (Edit: the quickest way is to set your frame count to 1; then back to the required maximum.)

Now you should have a scene where frame 1 is identical to the last frame of the previous one.

Good luck. If you're trying to do a six minute animation you'll need it. ;)