Dynamic link is buggy (it shows wrong frames of imported PPro project timelines way too often) and slow.
Try exporting your timeline using Quicktime PNG (Slightly lossy, but alpha support), Animation (Lossless, alpha support) or JPEG (lossy, no alpha, fast and small, good for most work) codecs. Import this to AE and do whatever you need.
Then export (CTRL+M) your AE comp back to Premiere using the same settings. These should survive multiple rendering passes without significant quality loss.
Great option is Cineform, but that might be expensive.
Hope this helps!