Ex-eircom, by the sounds of it? Me, too. Those VS deals back in the day were the bees knees!
A few things.
1. As you know, you have two separate pension schemes. Because the lump sum you got from eircom was more than ten years ago, it doesn't count against your lump sum limit from your current employment. So you can top that up with AVC contributions for the next five years. (Not just "last minute" contributions.)
2. You might want to look at taking a transfer value out of your deferred pension scheme. Normally this is strongly advised against for a DB scheme. But there's a couple of unique features here. First, it's very unusual in that you've already taken the lump sum element so you will only get an annual pension. Second, the eircom scheme is fully funded, but derisked and invested in low-risk, low-return bonds. That means there's unlikely to be discretionary increases for pensioners. If you transfer out (and the current finance act going through the Dail will allow you to) you can take 25% tax free straightaway on maturity and draw down the remainder as you choose.
3. You could also look at purchasing additional years in your current public service employment.