The Lion Theatre has been operating in the Red Lion Hotel, in Horncastle, for about 30 years.
The pub was boarded up in June after it closed to the public, prompting fears that performances would end there.
Horncastle Theatre Company's chair Shirley Moffat said it had made an offer of £80,000 but needed to raise more money for alterations and repairs.
Ms Moffat had been told by owners RBNB the group faced eviction at the end of February but have since managed to hang on for longer.
"We want to keep continuity and keep productions rolling, to keep people's morale up," she said.
"It's so difficult to have to come to meetings and tell the membership we still can't say for certain we'll have a future here.
"It's got everything we want, it's got the seats, it's got the stage. It's the right place to be."
The group has put in a bid of £80,000 and has asked for a response by the end of the week.
However, about £120,000 will be needed in total to conduct repairs and make alterations to its heating and electricity.
Ms Moffat said the theatre company had lots of support in Horncastle but would have to do some "serious fundraising" and "grant hunting" to be able to keep the theatre open.
A theatre group has put in a bid to buy its pub-based venue following concerns it would be evicted.