Barile -

if the clover does not come bac, or even if it does and the weeds are greater than 50% - I would replant - not reseed.

There are some specialty techniquies like spraying roundup then overseeding clover - but for my time and money - its tough to beat a good plowing - harrow/disc - lime/fertilize - cultipack - plant - cultipack - hope for light sustained rain, technique.

If you decide to replant - and you want a clover only plot - do not use a mix - even if its cheap or free - it' ll cost you more in the long run to fight the grasses. I' d suggest a 100% clover planting if the soil moisture is good and you are not in drought-like conditions - or seeding with 30-60 lbs/acre of an anual cereal grain like oats - for a nurse crop.