Overview
When you pause your campaign, you are pausing the promotion of that campaign. That means that no new advocates or shares will be generated for that campaign.
If the share is already out there, in a friend's inbox or posted to a blog, and a friend clicks on that link, that friend will still receive the landing experience and reward for that paused campaign. If that conversion is approved, the advocate will be rewarded with the reward from that paused campaign as well.
If an advocate clicks on a promotion link or call to action to share again, the advocate will be redirected to the new campaign. They will become an advocate and their shares will be linked to this live campaign. Therefore, by pausing you are preventing top of the funnel traffic from being generated, but conversions will come in and rewards will still go out from that paused campaign.
Example
Lindsey shares from the $10-$10 campaign to Jordan. The next day that campaign is paused and a $20 campaign is launched. Jordan clicks Lindsey's email (after the campaign was paused) and get's the $10 reward popup, just as his email said. He converts, and Lindsey gets $10 just as she expected.
Lindsey goes back the next day to share with Matt. Lindsey now sees the $20 campaign and shares the $20 with Matt.
How should I handle changes?
If you are making creative changes (not reward changes), then you can burst your new campaign and end your old campaign. This puts everyone immediately onto the new campaign.
If you are making reward changes you should use an overlap period of pausing one campaign.