Is 2 weeks realistic?
Two weeks is tight, but improvement is possible if you start close to your target already (e.g., CLB 7→7.5 or 8→8.5). For major jumps (CLB 6→8), 2 weeks won't be enough.
2-week sprint plan
Week 1: Do two full practice tests, identify your lowest section, then drill that section daily (20-30 min). Week 2: One full mock, plus three heavy drills on your weakest part. Zero new topics. Focus on speed and consistency.
Critical success factor
You must already be familiar with format and timing. If CELPIP is brand new to you, two weeks is not realistic. Prioritize format familiarity over perfection.