Why don’t we clear trapped emotions between lifetimes?

Many of the stuck emotions cleared during Soul Lab sessions are either from previous lifetimes, or seemingly from the spaces in between lifetimes. What’s up with that? If there really is a heaven to speak of, where the veil is lifted and we perceive all truth, why would we choose not to wipe our slate clean and rid ourselves of all stuck emotional energies during those intervals? And how, praytell, could we accumulate more stuck emotions during those intervals?