Any time you're asking the question of whether you should recollect data, I tend to say that you should go ahead and do that if possible (especially if you can figure out what was causing the baseline drift and how to get rid of that). That being said, there's a couple of options here, especially for the stronger signal data.
First, you might be able to use a buffer region just before the first small peak, and then do a linear baseline correction across the peaks, just on the downsloping side. If you make the range tight enough, there might not be that much drift, allowing you to get something that might be more reliable.
Second, REGALS can take a lot of playing around with. I'd recommend trying it both with and without subtracting buffer (e.g. fitting the buffer as a component, as well as the drift), and limiting the range for REGALS to where it starts to increase, around frame 215. You might also try cutting off some of the early frames and seeing what affect that has (basically trying to limit the amount of change that you're fitting).
If you send me the dataset I can take a quick look at it when I have time.
All the best.
Jesse Hopkins, PhD
BioCAT, Sector 18
Advanced Photon Source