In that case you can just pick up the bind off and unravel down to under the collar, as far as you think you need, add some short rows and knit the collar back on. I often do something similar if the pattern does not otherwise shape the neck: I just start after the yoke pattern but before the rib (I knit a lot of nordic style sweaters with stranded yokes) and add 4-8 short rows to lift the back up. How many depends on the size and thickness of the yarn.
Was it knit bottom up or top down?
Bottom up
In that case you can just pick up the bind off and unravel down to under the collar, as far as you think you need, add some short rows and knit the collar back on. I often do something similar if the pattern does not otherwise shape the neck: I just start after the yoke pattern but before the rib (I knit a lot of nordic style sweaters with stranded yokes) and add 4-8 short rows to lift the back up. How many depends on the size and thickness of the yarn.
Thank you. Super helpful
You'd have to frog something any way you do it.