You have to leave the price at the discount for as long as you promised to when you submitted the deal application, if I remember correctly. You check a box that says you pledge to leave the deal up for that length of time. Now, you can set the length of time from a day to a year (or more?) but if you don't do what you promised, you are subject to them sanctioning you for your next application(s). So, raising the price earlier than you contracted for is taking a big risk.
That aside, the question is always "what's your goal?" If your goal is to generate new readers by discounting a Book 1 and getting read-through, then it makes sense to leave it discounted as long as it's selling above its "normal" level, whatever that is. That's what I do. When the sales fall to about where they were at full price (which for a Book 1 is never above 3.99) then I raise it back to normal. It can always be discounted again.
If your goal is immediate money, rather than getting the book into as many hands as possible, especially if it's a standalone book, then you should only discount for a short period. In this case, your goal is to convert to a full-price range (70% royalty) at the peak of sales ranking, which is usually 24-48 hours after the BookBub runs. Just make sure you didn't promise a week and then raise it early. With this strategy, you can support your BB with post-run per-click ads (AA (former AMS) or Facebook, usually), which you can leave running for as long as you're getting a positive ROI from the ads. This synergizes nicely with the ranking boost you got from the promo, keeping your book higher and getting more sales.
