Should I put money into mortgage?

[Finlaggan]

I've got a bit of ready cash, enough to max out my overpayment for this year and then a bit I'm looking to invest elsewhere. However, our fixed rate finishes next summer and I'm wondering whether I should PI the lump sum in now and reduce my term by around 18 months as well as the overall debt or keep the cash to use when we reappraise our rate next year? Is it if any benefit to have cash ready when looking to buy a new mortgage product when ours expires next year? Thanks.

[BackforGood]

I always overpaid whatever I could as we went along. As long as you have enough cash for usual living + 'emergencies', then you might as well reduce your debt whenever you are able, IMO.
Never needed ready cash when remortgaging, just took out the next product for the amount we needed.