By this time of year all the herbaceous plants have died back and reduced to yellow/brown remnants of their former glory. Take the opportunity to rake any remains from the lawn where overhang has shaded out light and then look to reinstate the lawn edges. An opportune time to also prune back overhanging growth from tree canopies and other woody plants. This work allows you to take stock of the border lines you see as part of your garden design. Maybe this is the time to widen the border allowing the plant collection to develop. Otherwise use open weather conditions to cut out dead turf and reform the border edge with rolls of new turf. Ideally this new turf should have the same grass species make up as your lawn or come spring there may be differences in colour and growth rates between established and newly laid turf. Combine this task with raising sunken areas that have formed in the lawn. Use a half moon and turf float or spade to cut out and roll back the turf from the sunken area. Add soil and fold the turf back over the area. Ensure a close knit where the cut edges join to prevent desiccation.   

Edge of lawn damaged by herbaceous growth through summer
Repairing the lawn