So, your seeing "pretty heavy actvity" and you want to know if you should repitch???? I think your fine. I'm not sure I understand, but if you worried about your yeast cake being big, I wouldn't worry about it.
The yeast cake you speak about is more likely to be hops, break material, and probably some yeast. Leave it be for 3 weeks. If it makes you feel better you can agitate the fermenter , I mollest my carboy all the time.
