mono to mono knot to add line

[Bigdaddyhockey]

My son had an issue with his reel after getting stuck on the bottom and forgetting to put his finger on the spool when he released the tension. Long story short we had to cut off a good amount of line to fix the issue and now I want to add back the line he lost.

I've done plenty of knots for shock leaders, and mono to braid but never between 2 lines of the same type and diameter. Which knot do you guys use or recommend? Or am I better off just stripping off what is left and starting from scratch. Thanks.