Hi LaughingHyena,
I started on insulin in December 2010 and have had a similar experience. I have had on average 15 hypos a month for the last 3 months, but these have been slowly dropping off and this last week I have suddenly gone the other way and my insulin requirements have jumped. In discussion with my DSN I moved from twice daily levemir to once a day, and that did seem to help with lunchtime and early evening hypos. I also dropped my apidra doses, if not the ratios per se. I was having the same breakfast every day and dropped from 8u to 6u in the morning (strangely I now seem to need 12u, but there you go!). I've never had night time lows and my morning levels are stubbornly high, at about the 7ish mark, so it was breakfast to dinner that was the problem.
For me, this was a basal problem, but it's not like the different insulins know exactly which bit of glucose they are targeting so bolus also comes in to play. The standard advice seems to be change lantus 2u with at least 3 days between changes. I don't think this is terrible advice, and would leave a few days but might personally be inclined to be a bit more adventurous with the amount of lantus. I dropped fairly quickly from 24u levemir per day to 15u and this did really help. You need to make a decision based on your results though, obviously. What worked for me might not work for you.
Are you getting much advice from your DSN? Most of my changes were done after phone discussions with DSN and a face to face meeting to try and bottom out the problem.